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First Time AR15 Build - Please Help Me Not Be An Idiot

Franko

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May 19, 2018
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Southern California
I don’t know anything about AR15’s but want to be ready to build one as soon as California is forced to get rid of their “assault weapons” regulations by the Bruen Decision. My plan is to start accumulating parts now rather than trying to buy them once the rules are changed and 10 million other California gun owners are all trying to buy the same parts I want.

I want a build that I can use for home defense, civil unrest, and training courses I intend to take. I want this gun to be absolutely reliable, but I am not interested in wasting money either. I am looking for a sanity check on my selections (“those two parts don’t work together you moron”) and any feedback on my choices.

Lower – LMT Mars-L (the only part I currently have)

Lower Parts Kit – LMT

Trigger – Hiperfire Hitouch Reflex or Geissele Hi-Speed National Match (DMR springs); The Hiperfire doesn’t have the reputation for reliability like Geissele but I have no experience with two-stage triggers.

Buffer Kit – no idea; does this even matter?

Grip – Magpul MOE K2

Stock – Magpul STR Carbine Stock Mil-Spec

Upper – BCM Mk2 or Vltor MUR; the BCM seems like it’s the new hotness, but it appears that BCM doesn’t sell these to the general public anymore. Is it worth waiting and hoping or just go for it and buy a Vltor when I can find it?

Handguard – KAC URX4 or Vseven; I think the KAC is probably bulletproof but am looking at Vseven for weight savings. Are either of these compatible with the BCM upper or will I need something else? I am assuming they work with the Vltor.

Barrel (16 inch) – FN HF, Noveske N4, or Criterion Core. Leaning towards Noveske because the profile and it weighs less than the FN and the Criterion is at least a 6 month wait (I believe that all the barrels are made by FN). Really looking for feedback here as I expect this is where accuracy is made or broken. Is 1.5 MOA a reasonable expectation for accuracy with decent factory ammo or progressively reloaded ammo? If necessary, I have the time to wait while Compass Lake cuts me a SS barrel.

Gas Tube – no idea if this even matters

Gas Block – Vseven titanium; If I go with pinned (and not clamped) will I need to have someone modify my barrel?

Bolt Carrier Group – Bootleg Adjustable Bolt Carrier or Rubber City Armory Standard Mass 5.56 x 45(223) M16 BCG Complete w/ Adjustable Gas Key. I have no idea if one is better or worse than the other. I am looking at these because my hope is that eventually I will be able to use a suppressor but wanted a non-adjustable gas block for reliability.

Charging Handle – PRI M-84 Gasbuster with combat latch

Muzzle Device – Hellfire linear flash suppressor

I will be hitting up the optics forum for help with the optic, mounts, and BUIS. At some point I will also start a thread on things I will need for tools (cleaning, maintenance, etc.).

Thanks for reading this.
 
What is the combined cost of all those parts you listed above?
 
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Im wondering if it would make more sense (lower overall cost, quicker acquisition process) to just buy a factory rifle from a reputable manufacturer (LMT, DD, Colt, LWRC, JP, BCM, etc) unless you have some specific parts requirements that cant otherwise be met cost effectively after purchasing the full up gun…
 
Can't buy factory as these kinds of guns are still illegal in CA and the prices are going to go completely crazy when millions of Californians start buying once the law does change. I'm trying to get ahead of this, and I do also like to play with Leggos...
 
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I don’t know anything about AR15’s but want to be ready to build one as soon as California is forced to get rid of their “assault weapons” regulations by the Bruen Decision. My plan is to start accumulating parts now rather than trying to buy them once the rules are changed and 10 million other California gun owners are all trying to buy the same parts I want.

I want a build that I can use for home defense, civil unrest, and training courses I intend to take. I want this gun to be absolutely reliable, but I am not interested in wasting money either. I am looking for a sanity check on my selections (“those two parts don’t work together you moron”) and any feedback on my choices.

Trigger – Hiperfire Hitouch Reflex or Geissele Hi-Speed National Match (DMR springs); The Hiperfire doesn’t have the reputation for reliability like Geissele but I have no experience with two-stage triggers.

Buffer Kit – no idea; does this even matter?

Upper – BCM Mk2 or Vltor MUR; the BCM seems like it’s the new hotness, but it appears that BCM doesn’t sell these to the general public anymore. Is it worth waiting and hoping or just go for it and buy a Vltor when I can find it?

Handguard – KAC URX4 or Vseven; I think the KAC is probably bulletproof but am looking at Vseven for weight savings. Are either of these compatible with the BCM upper or will I need something else? I am assuming they work with the Vltor.

Gas Block – Vseven titanium; If I go with pinned (and not clamped) will I need to have someone modify my barrel?

Bolt Carrier Group – Bootleg Adjustable Bolt Carrier or Rubber City Armory Standard Mass 5.56 x 45(223) M16 BCG Complete w/ Adjustable Gas Key. I have no idea if one is better or worse than the other. I am looking at these because my hope is that eventually I will be able to use a suppressor but wanted a non-adjustable gas block for reliability.

Charging Handle – PRI M-84 Gasbuster with combat latch

Muzzle Device – Hellfire linear flash suppressor
I am only commenting on the parts that I have used or currently used.

Trigger - if you are worried about a do it all including civil unrest I would use the Geissele SSA or SSA-E (the other triggers are fine just not battle proven)

Buffer Kit - Yes it matters. I very much like the JP Silent Capture. I also like the Geissele braided spring and the VLTOR A5 system.

The last rifle I built used the VLTOR upper (recommended in the forum). I have no complaints.

Handguard - There are a ton of good handguards, depends on your shooting style and barrel length. The KAV, DD and Geissele are all fantastic.

Gas Block & BCG - I have always like milspec BCGs, the RCA is fine. I have one rifle with an adjustable gas block. The JP system is good as well as the Superlative. I have never used a BCG with adjustable gas.

The PRI is good. I also like the Radian and Geissele

Muzzle Device - depends if you are going to use a can on your rifle. For instance I have a couple of Dead Air suppressors so I use their muzzle device with their mounting system. Surefire and others have them. It seems like lots of the precision guys prefer thread on cans.
 
Can't buy factory as these kinds of guns are still illegal in CA and the prices are going to go completely crazy when millions of Californians start buying once the law does change. I'm trying to get ahead of this, and I do also like to play with Leggos...
When/how soon do you anticipate the law changing?
 
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I don’t know anything about AR15’s but want to be ready to build one as soon as California is forced to get rid of their “assault weapons” regulations by the Bruen Decision. . . .

It is my understanding that the Bruen Decision has to do with concealed carry and has nothing to do with assault weapons.

Your best bet is to leave California, I did!
 
It is my understanding that the Bruen Decision has to do with concealed carry and has nothing to do with assault weapons.
California and 9th Circuit Federal Courts have been intentionally using the wrong method to decide if a gun law was permitted by the 2nd Amendment. The language of the Bruen decision provides for a new and very strict testing method that should result in most if not all California gun laws (magazine capacity, handgun bans, AW ban, etc.) being found to be unconstitutional. Now it's just a waiting game. I'm probably being wildly optimistic on the timeline, but a man can dream...

Once the laws do fall millions of California gun owners are going to make the guns and gun parts even scarcer and more expensive than they are now. That's the excuse I am using to justify spending money on guns. However, the feedback I am getting is making me rethink. Maybe just save my cash and wait.
 
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I want a build that I can use for home defense, civil unrest, and training courses I intend to take. I want this gun to be absolutely reliable, but I am not interested in wasting money either. I am looking for a sanity check on my selections (“those two parts don’t work together you moron”) and any feedback on my choices.

Before you get too wrapped around the axle about things you should consider a more specific purpose behind the rifle. "Home defense" might be 10 different things to 10 different people. In my opinion this is not a specific enough purpose and will make your life more complicated.

For example I live way out in the country so having 'distance' is a good option. Also 'precision' is another good option that can be rolled into one.

On the other hand I have others with a 1x Aimpoint RDS on them. Avoiding wasting money on unnecessary components for the given purpose will be a good idea. With a 1x red dot to put a barrel from some custom shop with a 9 month wait is IMO not worth it. Typically those rifles will be used in much shorter engagement distances while running around moving etc.

With a good barrel, no matter how good it is, it requires equal levels of ammo. In other words if you get some high dollar barrel and shoot cheapo 55 grain ammo you will get a 1-2 MOA gun at best. In other words you need to consider your ammo choices and rifle purposes before going deep on these expensive barrels. There is more than one way to tackle that dilemma... but it's worth consideration.

Stock – Magpul STR Carbine Stock Mil-Spec

The stock IMO matters a whole lot. I have a couple of rifles with the Magpul SLK on them and I like it a lot. A lot better than the one you mentioned for those particular rifles' given layouts and purposes. On the other hand I have other rifles that there is no way I would want an SLK on. For more precision centered rifles something that has a better option to shoot off a rear bag is much better. Again, it all depends on a much more specific need of the given rifle. This again goes back to sharpening up exactly what you want the rifle to do.

Barrel (16 inch) – FN HF, Noveske N4, or Criterion Core. Leaning towards Noveske because the profile and it weighs less than the FN and the Criterion is at least a 6 month wait (I believe that all the barrels are made by FN). Really looking for feedback here as I expect this is where accuracy is made or broken. Is 1.5 MOA a reasonable expectation for accuracy with decent factory ammo or progressively reloaded ammo? If necessary, I have the time to wait while Compass Lake cuts me a SS barrel.

Gas Tube – no idea if this even matters

Gas Block – Vseven titanium; If I go with pinned (and not clamped) will I need to have someone modify my barrel?

Bolt Carrier Group – Bootleg Adjustable Bolt Carrier or Rubber City Armory Standard Mass 5.56 x 45(223) M16 BCG Complete w/ Adjustable Gas Key. I have no idea if one is better or worse than the other. I am looking at these because my hope is that eventually I will be able to use a suppressor but wanted a non-adjustable gas block for reliability.

Charging Handle – PRI M-84 Gasbuster with combat latch
Barrels and all that will depend on what you want to do. Having to wait for 9 months for a match grade barrel that you will feed cheap ammo through and shoot with a 1x dot at 100 yards is a complete waste of money and time. Off the shelf barrels are just fine for most general purpose shooting IMO.

Gas tubes and all that do matter. The details of little parts like this in the end are a big deal especially if guns will be run really hard. In other words go with a reputable name brand.

Also there is zero reason to go with a titanium block. That is unless the rest of the rifle is specified to be light weight, save your money and go with something more traditional.

Getting some adjustable carrier and all that is a total waste of money. The exception to that is if you plan on moving someplace where you can own a suppressor. Outside of suppressed use skip the adjustable carrier. Same thing with a 'gas buster' charging handle.

In any case, to sum up my feelings about your post, you put up specific parts, but not a specific enough layout or a specific enough purpose behind the proposed rifle. Your general criteria is akin to saying 'I want a car that can drive on the freeway but also can be driven in the city' but then you listed what size rims you want and what kind of wheels it will have. Well that's not specific enough.
 
Before you get too wrapped around the axle about things you should consider a more specific purpose behind the rifle. "Home defense" might be 10 different things to 10 different people. In my opinion this is not a specific enough purpose and will make your life more complicated.

For example I live way out in the country so having 'distance' is a good option. Also 'precision' is another good option that can be rolled into one.

On the other hand I have others with a 1x Aimpoint RDS on them. Avoiding wasting money on unnecessary components for the given purpose will be a good idea. With a 1x red dot to put a barrel from some custom shop with a 9 month wait is IMO not worth it. Typically those rifles will be used in much shorter engagement distances while running around moving etc.

With a good barrel, no matter how good it is, it requires equal levels of ammo. In other words if you get some high dollar barrel and shoot cheapo 55 grain ammo you will get a 1-2 MOA gun at best. In other words you need to consider your ammo choices and rifle purposes before going deep on these expensive barrels. There is more than one way to tackle that dilemma... but it's worth consideration.



The stock IMO matters a whole lot. I have a couple of rifles with the Magpul SLK on them and I like it a lot. A lot better than the one you mentioned for those particular rifles' given layouts and purposes. On the other hand I have other rifles that there is no way I would want an SLK on. For more precision centered rifles something that has a better option to shoot off a rear bag is much better. Again, it all depends on a much more specific need of the given rifle. This again goes back to sharpening up exactly what you want the rifle to do.


Barrels and all that will depend on what you want to do. Having to wait for 9 months for a match grade barrel that you will feed cheap ammo through and shoot with a 1x dot at 100 yards is a complete waste of money and time. Off the shelf barrels are just fine for most general purpose shooting IMO.

Gas tubes and all that do matter. The details of little parts like this in the end are a big deal especially if guns will be run really hard. In other words go with a reputable name brand.

Also there is zero reason to go with a titanium block. That is unless the rest of the rifle is specified to be light weight, save your money and go with something more traditional.

Getting some adjustable carrier and all that is a total waste of money. The exception to that is if you plan on moving someplace where you can own a suppressor. Outside of suppressed use skip the adjustable carrier. Same thing with a 'gas buster' charging handle.

In any case, to sum up my feelings about your post, you put up specific parts, but not a specific enough layout or a specific enough purpose behind the proposed rifle. Your general criteria is akin to saying 'I want a car that can drive on the freeway but also can be driven in the city' but then you listed what size rims you want and what kind of wheels it will have. Well that's not specific enough.
Understood. I will try to lay it out:

My primary use case is home/self defense in the event of disaster or civil unrest. My expected engagement range is going to be out to approximately 400 yards. I don't expect to use it to clear my house if something goes bump in the middle of the night. If that happens I'm going to call 911 and yell at the intruder from the safety of my bedroom, because nothing outside my bedroom is worth the legal complications of a shooting. If they still try to enter my bedroom then the shooting will start.

My secondary use will be taking training classes and potentially shooting the crap out of it as that is the only way I know how to get proficient with a weapon. So I expect significant wear and tear. This will not be a range toy.

My priorities in order of importance are:
  1. Reliability, I want this to work every time all the time
  2. Handling, weight and length play into this
  3. Accuracy, I would love a 1 MOA gun but accept that it's probably going to be a 1.5 to 2 MOA gun with a chromed barrel and good ammo
  4. I have hopes of putting a suppressor on it in the future but it sounds like I need to rethink that
I have learned to "buy once and cry once" as messing around with substandard equipment just wastes my time and usually ends being as expensive as buying the good stuff first.

I am getting the feeling that I should just pay someone to buy me a new LMT and send me everything but the lower and be done with it.

Thanks for the help.
 
VLTOR MUR won’t work with MARS. The FCD receiver is what you seek.

Geissele super 42 for buffer and spring in an LMT enhanced buffer tube.

I would go with a better barrel. Noveske is super over rated. Proof SS is awesome. DD is good if you use have chrome lined.

Neither of those triggers are what I’d use on an all around type AR. Larue MBT-2S is amazing as is Geissele SD-E.

SLR clamp on gas block.

KAC friends are over rated AF.
 
Can you buy a DI LWRCi that's CA compliant and swap out the compliance parts in the future? That's a fantastic, duty grade rifle going for $1,440 on Eurooptic right now.
 
Can you buy a DI LWRCi that's CA compliant and swap out the compliance parts in the future? That's a fantastic, duty grade rifle going for $1,440 on Eurooptic right now.
Yes, so long as it's CA compliant I can do that. It doesn't appeal to my "gun Leggo" fantasy and I might get some parts I'm not a fan of but it's a possibility.
 
Understood. I will try to lay it out:

My primary use case is home/self defense in the event of disaster or civil unrest. My expected engagement range is going to be out to approximately 400 yards. I don't expect to use it to clear my house if something goes bump in the middle of the night. If that happens I'm going to call 911 and yell at the intruder from the safety of my bedroom, because nothing outside my bedroom is worth the legal complications of a shooting. If they still try to enter my bedroom then the shooting will start.

My secondary use will be taking training classes and potentially shooting the crap out of it as that is the only way I know how to get proficient with a weapon. So I expect significant wear and tear. This will not be a range toy.

My priorities in order of importance are:
  1. Reliability, I want this to work every time all the time
  2. Handling, weight and length play into this
  3. Accuracy, I would love a 1 MOA gun but accept that it's probably going to be a 1.5 to 2 MOA gun with a chromed barrel and good ammo
  4. I have hopes of putting a suppressor on it in the future but it sounds like I need to rethink that
I have learned to "buy once and cry once" as messing around with substandard equipment just wastes my time and usually ends being as expensive as buying the good stuff first.

I am getting the feeling that I should just pay someone to buy me a new LMT and send me everything but the lower and be done with it.

Thanks for the help.
Keep in mind that not long ago I was in the same boat as you (in a sense). I had no idea what to get and was basically stifled by so many choices. I had no idea what I was getting or why.

Fortunately I took the time to REALLY step back and think through what a very purpose specific rifle would look like. Everything from balance to what kind of ammo was taken into account. In my experience this led me to much much more 'shootable' rifles. The pure enjoyment factor of shooting any of my rifles is for me way better than just a compromise of stuff. There is a reason why people have more than one rifle.

Getting a rifle to be extremely reliable is not that hard if you use quality components. If you have quality parts then the onus is on you to put them together in a manner that will not fail under use.

As for barrels 'chrome lined' is really old school. There are cheap barrels out there that can give you great performance. After you spend anywhere from $15,000 to $20,000 on ammo (or more) you can just buy another $150 barrel and be on your way.

Like I said before the best thing in my opinion is to match the barrel to the ammo. If you want extreme precision you need to reload or at very least try to buy nice $2 per round ammo (if you can find it). With one of my rifles I shot a 10 shot group that I could cover all the edges up with a dime (at 100 yards). I haven't done that in a while (shoot that gun for groups) but you can get them into the half minute category if you try. Mine has an off the shelf barrel with lots of load development. In my opinion the latter (the load development) is in ways more important that just having an expensive barrel.

Again it boils back down to how precise you really want to be.

I still think going back to the car analogy that you need to ask 'am I going to be hauling stuff?' 'what kind of gas mileage do I really want?' 'How many passengers do I need to carry around?'...will be a lot more useful in making decisions. If I am going to haul firewood then a toyota corolla is off the list. But if my priority is to not spend so much money on gas AND I won't have a lot of people to carry around then that Corolla is a good option.

Taking time to step back and analyze what and how (and how much) you will shoot will in the end give you more overall enjoyment of the end product.
 
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The older Colts were reliable but dated. Just basic AR’s that worked. No idea about new ones. Not sure how they could screw it up. The unreliable AR’s I have seen have been home builds by first time AR owners.
 
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If you're in SoCal, go visit Riflegear in Fountain Valley.
It's just around the corner from the Fry's electronics (if that's still there??).
You don't have to buy anything, but the guys behind the counter are pretty kewl for the most part and will let you handle shit.
Handling shit is good, you can easily tell the quality levels by looking and touching (well, for the most part).

BTW, I built my 1st AR, my 2nd, my 3rd.....hell, I've never bought a "built" AR in my life and never intend to.
And yes, I've built every AR308 (large frame) that I've ever owned....and all of them have zero issues.
You just have to pay attention to what you're buying, and doing, with those parts.
 
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Can you buy a DI LWRCi that's CA compliant and swap out the compliance parts in the future? That's a fantastic, duty grade rifle going for $1,440 on Eurooptic right now.
That is a really good idea. And I agree, it is a fantastic rifle for the money.
 
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Since you are in CA, go to calguns marketplace and search for a good deal on a descent LMT/KAC/LWRC upper or an entire upper. No need to wait for things to be restocked. You will need to build out the lower since you already have that but the parts are easy to get online, usually stocked
 
So this whole thread is predicated on the 9th circuit, CA legislators, the state executive branch, various bureaus and agencies, and local governments suddenly saying “ok, we give,” all because of one SC opinion?

Did you recently move to CA?
 
So this whole thread is predicated on the 9th circuit, CA legislators, the state executive branch, various bureaus and agencies, and local governments suddenly saying “ok, we give,” all because of one SC opinion?

Did you recently move to CA?
No. It's based on irrational exuberance and the love of guns...
 
Can't buy factory as these kinds of guns are still illegal in CA and the prices are going to go completely crazy when millions of Californians start buying once the law does change. I'm trying to get ahead of this, and I do also like to play with Leggos...

Yes, you can buy a factory AR15. You must order from the manufacturer a California compliant grip. Or if you go through a dealer, make sure they will install this grip before they transfer the AR to you.

Here are the grips you need to buy.

 
Yes, so long as it's CA compliant I can do that. It doesn't appeal to my "gun Leggo" fantasy and I might get some parts I'm not a fan of but it's a possibility.
Getting the LWRC or DD that are still legal to be sold in CA is the way I would go. That way you have your defense rifle on hand.

Then buy the parts you want to replace and have them ready. But I wouldn't hold your breath that it will be any time soon. And if the shooting starts, then no one will care about compliance.

Instead of worrying about amassing a bunch of gucci parts, I would suggest you put that money towards ammo right now.
 
Since you are in CA, go to calguns marketplace and search for a good deal on a descent LMT/KAC/LWRC upper or an entire upper. No need to wait for things to be restocked. You will need to build out the lower since you already have that but the parts are easy to get online, usually stocked
The market place was the only thing I missed after being perma-banned from CalGuns due to making the LEO fanbois cry.

But then I moved to AZ and said fuck you to CA. I hope it goes down in flames.
 
Yes, you can buy a factory AR15. You must order from the manufacturer a California compliant grip. Or if you go through a dealer, make sure they will install this grip before they transfer the AR to you.

Here are the grips you need to buy.

You also need an non-adjustable or fixed stock. Or at least a stock that requires a tool to adjust. Also, no flash hiders. Brakes are good to go.
Stock-lok works well for me: Stock-Lok
 
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I don’t know anything about AR15’s but want to be ready to build one as soon as California is forced to get rid of their “assault weapons” regulations by the Bruen Decision. My plan is to start accumulating parts now rather than trying to buy them once the rules are changed and 10 million other California gun owners are all trying to buy the same parts I want.

I want a build that I can use for home defense, civil unrest, and training courses I intend to take. I want this gun to be absolutely reliable, but I am not interested in wasting money either. I am looking for a sanity check on my selections (“those two parts don’t work together you moron”) and any feedback on my choices.

Lower – LMT Mars-L (the only part I currently have)

Lower Parts Kit – LMT

Trigger – Hiperfire Hitouch Reflex or Geissele Hi-Speed National Match (DMR springs); The Hiperfire doesn’t have the reputation for reliability like Geissele but I have no experience with two-stage triggers.

Buffer Kit – no idea; does this even matter?

Grip – Magpul MOE K2

Stock – Magpul STR Carbine Stock Mil-Spec

Upper – BCM Mk2 or Vltor MUR; the BCM seems like it’s the new hotness, but it appears that BCM doesn’t sell these to the general public anymore. Is it worth waiting and hoping or just go for it and buy a Vltor when I can find it?

Handguard – KAC URX4 or Vseven; I think the KAC is probably bulletproof but am looking at Vseven for weight savings. Are either of these compatible with the BCM upper or will I need something else? I am assuming they work with the Vltor.

Barrel (16 inch) – FN HF, Noveske N4, or Criterion Core. Leaning towards Noveske because the profile and it weighs less than the FN and the Criterion is at least a 6 month wait (I believe that all the barrels are made by FN). Really looking for feedback here as I expect this is where accuracy is made or broken. Is 1.5 MOA a reasonable expectation for accuracy with decent factory ammo or progressively reloaded ammo? If necessary, I have the time to wait while Compass Lake cuts me a SS barrel.

Gas Tube – no idea if this even matters

Gas Block – Vseven titanium; If I go with pinned (and not clamped) will I need to have someone modify my barrel?

Bolt Carrier Group – Bootleg Adjustable Bolt Carrier or Rubber City Armory Standard Mass 5.56 x 45(223) M16 BCG Complete w/ Adjustable Gas Key. I have no idea if one is better or worse than the other. I am looking at these because my hope is that eventually I will be able to use a suppressor but wanted a non-adjustable gas block for reliability.

Charging Handle – PRI M-84 Gasbuster with combat latch

Muzzle Device – Hellfire linear flash suppressor

I will be hitting up the optics forum for help with the optic, mounts, and BUIS. At some point I will also start a thread on things I will need for tools (cleaning, maintenance, etc.).

Thanks for reading this.
For learning how to do it all, nothing beats Brownell's DVD on the subject.
Brownells AR building video
 
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I don’t know anything about AR15’s but want to be ready to build one as soon as California is forced to get rid of their “assault weapons” regulations by the Bruen Decision. My plan is to start accumulating parts now rather than trying to buy them once the rules are changed and 10 million other California gun owners are all trying to buy the same parts I want.

I want a build that I can use for home defense, civil unrest, and training courses I intend to take. I want this gun to be absolutely reliable, but I am not interested in wasting money either. I am looking for a sanity check on my selections (“those two parts don’t work together you moron”) and any feedback on my choices.

Lower – LMT Mars-L (the only part I currently have)

Lower Parts Kit – LMT

Trigger – Hiperfire Hitouch Reflex or Geissele Hi-Speed National Match (DMR springs); The Hiperfire doesn’t have the reputation for reliability like Geissele but I have no experience with two-stage triggers.

Buffer Kit – no idea; does this even matter?

Grip – Magpul MOE K2

Stock – Magpul STR Carbine Stock Mil-Spec

Upper – BCM Mk2 or Vltor MUR; the BCM seems like it’s the new hotness, but it appears that BCM doesn’t sell these to the general public anymore. Is it worth waiting and hoping or just go for it and buy a Vltor when I can find it?

Handguard – KAC URX4 or Vseven; I think the KAC is probably bulletproof but am looking at Vseven for weight savings. Are either of these compatible with the BCM upper or will I need something else? I am assuming they work with the Vltor.

Barrel (16 inch) – FN HF, Noveske N4, or Criterion Core. Leaning towards Noveske because the profile and it weighs less than the FN and the Criterion is at least a 6 month wait (I believe that all the barrels are made by FN). Really looking for feedback here as I expect this is where accuracy is made or broken. Is 1.5 MOA a reasonable expectation for accuracy with decent factory ammo or progressively reloaded ammo? If necessary, I have the time to wait while Compass Lake cuts me a SS barrel.

Gas Tube – no idea if this even matters

Gas Block – Vseven titanium; If I go with pinned (and not clamped) will I need to have someone modify my barrel?

Bolt Carrier Group – Bootleg Adjustable Bolt Carrier or Rubber City Armory Standard Mass 5.56 x 45(223) M16 BCG Complete w/ Adjustable Gas Key. I have no idea if one is better or worse than the other. I am looking at these because my hope is that eventually I will be able to use a suppressor but wanted a non-adjustable gas block for reliability.

Charging Handle – PRI M-84 Gasbuster with combat latch

Muzzle Device – Hellfire linear flash suppressor

I will be hitting up the optics forum for help with the optic, mounts, and BUIS. At some point I will also start a thread on things I will need for tools (cleaning, maintenance, etc.).

Thanks for reading this.
Uh, I taught myself 30-years ago by reading an Army manual. How about starting with a basic build? Buy yourself one of roll-out mats imprinted with the list of AR parts for starters.
 
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I don’t know anything about AR15’s but want to be ready to build one as soon as California is forced to get rid of their “assault weapons” regulations by the Bruen Decision. My plan is to start accumulating parts now rather than trying to buy them once the rules are changed and 10 million other California gun owners are all trying to buy the same parts I want.

I want a build that I can use for home defense, civil unrest, and training courses I intend to take. I want this gun to be absolutely reliable, but I am not interested in wasting money either. I am looking for a sanity check on my selections (“those two parts don’t work together you moron”) and any feedback on my choices.

Lower – LMT Mars-L (the only part I currently have)

Lower Parts Kit – LMT

Trigger – Hiperfire Hitouch Reflex or Geissele Hi-Speed National Match (DMR springs); The Hiperfire doesn’t have the reputation for reliability like Geissele but I have no experience with two-stage triggers.

Buffer Kit – no idea; does this even matter?

Grip – Magpul MOE K2

Stock – Magpul STR Carbine Stock Mil-Spec

Upper – BCM Mk2 or Vltor MUR; the BCM seems like it’s the new hotness, but it appears that BCM doesn’t sell these to the general public anymore. Is it worth waiting and hoping or just go for it and buy a Vltor when I can find it?

Handguard – KAC URX4 or Vseven; I think the KAC is probably bulletproof but am looking at Vseven for weight savings. Are either of these compatible with the BCM upper or will I need something else? I am assuming they work with the Vltor.

Barrel (16 inch) – FN HF, Noveske N4, or Criterion Core. Leaning towards Noveske because the profile and it weighs less than the FN and the Criterion is at least a 6 month wait (I believe that all the barrels are made by FN). Really looking for feedback here as I expect this is where accuracy is made or broken. Is 1.5 MOA a reasonable expectation for accuracy with decent factory ammo or progressively reloaded ammo? If necessary, I have the time to wait while Compass Lake cuts me a SS barrel.

Gas Tube – no idea if this even matters

Gas Block – Vseven titanium; If I go with pinned (and not clamped) will I need to have someone modify my barrel?

Bolt Carrier Group – Bootleg Adjustable Bolt Carrier or Rubber City Armory Standard Mass 5.56 x 45(223) M16 BCG Complete w/ Adjustable Gas Key. I have no idea if one is better or worse than the other. I am looking at these because my hope is that eventually I will be able to use a suppressor but wanted a non-adjustable gas block for reliability.

Charging Handle – PRI M-84 Gasbuster with combat latch

Muzzle Device – Hellfire linear flash suppressor

I will be hitting up the optics forum for help with the optic, mounts, and BUIS. At some point I will also start a thread on things I will need for tools (cleaning, maintenance, etc.).

Thanks for reading this.
One doesn't necessarily save money on a quality build over shopping around for a upper quality AR, but you do get the specific features you want in a self build, and are certainly more familiar with your finished firearm. Both Brownells and MidwayUSA have great free on-iine How To Videos in AR building, also sell any tools needed. American Gunsmithing Institute, AGI, in Napa, California has several videos on all aspects of AR building, troubleshooting.....as well as most other gun platforms. AGI videos are typically abut $39 each, some more, seasonally on sale -33 to -50%.....patience pays.....it'd the hunt, not the kill. Go in with a couple buddies to share, lower cost of videos/tools. Also, don;t forget YouTube. ARs are the Lincoln Logs/Tinker Toys/Legos of firearms. Happy tinkering.
 
No one should need anything more than a youtube vid to put an AR together. A bit of reading here- before buying parts and beginning the build- will suss out any issues that one might reasonably expect to encounter.

The only necessary tools that the average tinkerer is likely not to already have are; an AR armorer's wrench and a upper receiver vice block.

That said, I think an AR novice is well served in buying a factory built gun before descending down the rabbit hole of building a rifle.
 
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I have the AGI video as well as the Brownells video. The Brownells is VASTLY better.
 
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I don’t know anything about AR15’s but want to be ready to build one as soon as California is forced to get rid of their “assault weapons” regulations by the Bruen Decision. My plan is to start accumulating parts now rather than trying to buy them once the rules are changed and 10 million other California gun owners are all trying to buy the same parts I want.

I want a build that I can use for home defense, civil unrest, and training courses I intend to take. I want this gun to be absolutely reliable, but I am not interested in wasting money either. I am looking for a sanity check on my selections (“those two parts don’t work together you moron”) and any feedback on my choices.

Lower – LMT Mars-L (the only part I currently have)

Lower Parts Kit – LMT

Trigger – Hiperfire Hitouch Reflex or Geissele Hi-Speed National Match (DMR springs); The Hiperfire doesn’t have the reputation for reliability like Geissele but I have no experience with two-stage triggers.

Buffer Kit – no idea; does this even matter?

Grip – Magpul MOE K2

Stock – Magpul STR Carbine Stock Mil-Spec

Upper – BCM Mk2 or Vltor MUR; the BCM seems like it’s the new hotness, but it appears that BCM doesn’t sell these to the general public anymore. Is it worth waiting and hoping or just go for it and buy a Vltor when I can find it?

Handguard – KAC URX4 or Vseven; I think the KAC is probably bulletproof but am looking at Vseven for weight savings. Are either of these compatible with the BCM upper or will I need something else? I am assuming they work with the Vltor.

Barrel (16 inch) – FN HF, Noveske N4, or Criterion Core. Leaning towards Noveske because the profile and it weighs less than the FN and the Criterion is at least a 6 month wait (I believe that all the barrels are made by FN). Really looking for feedback here as I expect this is where accuracy is made or broken. Is 1.5 MOA a reasonable expectation for accuracy with decent factory ammo or progressively reloaded ammo? If necessary, I have the time to wait while Compass Lake cuts me a SS barrel.

Gas Tube – no idea if this even matters

Gas Block – Vseven titanium; If I go with pinned (and not clamped) will I need to have someone modify my barrel?

Bolt Carrier Group – Bootleg Adjustable Bolt Carrier or Rubber City Armory Standard Mass 5.56 x 45(223) M16 BCG Complete w/ Adjustable Gas Key. I have no idea if one is better or worse than the other. I am looking at these because my hope is that eventually I will be able to use a suppressor but wanted a non-adjustable gas block for reliability.

Charging Handle – PRI M-84 Gasbuster with combat latch

Muzzle Device – Hellfire linear flash suppressor

I will be hitting up the optics forum for help with the optic, mounts, and BUIS. At some point I will also start a thread on things I will need for tools (cleaning, maintenance, etc.).

Thanks for reading this.
This is the kind of thing that "advice" and "research" will only take you so far.

There is an abundance of great advice and basically a "formula" for putting together a good AR.

But, at least in my experience, you gotta get your hands on it, get some experience with it, and then you'll "know" exactly what you want... for the time being.

The more I learn about rifles and shooting, the more I realize that I "bought the wrong stuff" when I decided to spend my money on good out-of-the-box rifles. Nothing wrong with the products themselves. Just that, if I knew then what I know now, I'd have done things differently (example: there would be a KAC in my safe right now, along with some Centurion Arms stuff, and a few other things I'd have done different).

Anyway, take the advice that sounds best to you, and then learn from there. Who knows? Maybe you'll nail it the first time around.
 
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I'll toss my .02 cents, which is just my opinion which you may take or leave what you will. A lot of good advice already here, like buying a complete LMT or LWRC(something along those lines) and shoot it to familiarize yourself with the platform, get a feel for what you like, it will almost certainly save you time, money, and frustration in the long run. I personally am a "hard way" kind of guy, and like to live and learn, while doing my best to avoid mistakes along the way, so I built my first AR, and everyone since(somewhere in the area of 40-50 AR's now), and I've noticed the more I built, the way I went about selecting components evolved bit by bit as I got a better grasp on what I wanted and for what purpose it was to be used for. Like one thing I do with absolutely every single AR I construct is I have the gas block pinned to the barrel(which BTW I think if the price isn't an issue for you, the V7 titanium set screw gas block is a good way to go, their barrels are the bees-knees as well with a lifetime warranty!!!). The main thing though would be to source all your components from reputable companies, the last thing you want is a crappy gas block blow on you under hard use, or a gas key screw shear off and really mess up your day. Another thing to not cheap out on are magazines, most malfunctions can usually be contributed to the magazine, so I stick with either Magpul P-Mags or Lancer mags. I could go on forever, so I'll stop here, being everything else I can think of has been covered, I think. OH, tools, I'm sure you've researched a list of tools you'll need for assembling/disassembling/maintaining your AR collection(it'll turn in to one, trust me), whatever you choose, buy GOOD tools, like you said, buy once, cry once, and those tools will serve you well likely the rest of your life.
 
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After building/buying several ARs over the years and using some in training here is what I built.
ADM UIC ambi lower
Vltor MUR upper
Vltor A5 buffer system
Vltor Emod stock
Fortis castle nut system
Geissele SD-3G trigger
Criterion 14.5" Hybrid barrel with mid-length gas
Geissele fixed gas block
Geissele MK4 13.5" rail
Radian Raptor SD charging handle
Bootleg adjustable bcg (is not working, hopefully will be replaced by Bootleg)
JP Enterprises enhanced bolt
Radian Talon Ambi safety
ADM Recon mount
Steiner PX4i
As mentioned, unless you plan on using the gun suppressed the risks outweigh the benefits with adjustable bolt carriers or gas blocks (for a rifle used in this context). Given what you want to do with this rifle I would have the gas block pinned or at least have the barrel dimpled. Factor in the cost for tools that will be needed to assemble the rifle. At minimum a BEV block, armorers wrench (I use Magpul's), barrel nut wrench, torque wrench, punches... Im probably leaving some stuff out.
My rifle isn't light, but its very stout and well balanced. Its also exceptionally easy to shoot.
Given my proclivity to suppressed shooting I will likely be moving to piston systems from here on out.
You've got the time obviously, I'd put together a complete LMT piston system with their bolt carrier/bolt, and all the rest. Ive never heard a bad thing about them. As far as butt stock and pistol grip, I think its pretty tough to go wrong with Magpul. The 14.5" is my only AR that doesn't have a Magpul stock. Every rifle I own that accepts AR style grips (including the SCAR with modifications) uses a Magpul MOE+ or Magpul K2+
 
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The only deserving upper for an LMT MARS-L lower is an LMT monolithic upper, hosting an regular LMT barrel, or a match-grade barrel converted by D Wilson (if you want to do groups)...
 
I haven't really considered prices by my ballpark guess is 2200 to 2500.

You should be able to buy 3 or maybe even 4 AR-15s for that kind of money. It seems that most of you who have posted in this tread are far more invested in marketing than actually shooting.

If you like a certain handguard, or trigger, or stock or whatever, buy it and enjoy. Other than that, it does not take thousands of dollars to get a reliable AR-15.
 
You should be able to buy 3 or maybe even 4 AR-15s for that kind of money. It seems that most of you who have posted in this tread are far more invested in marketing than actually shooting.

If you like a certain handguard, or trigger, or stock or whatever, buy it and enjoy. Other than that, it does not take thousands of dollars to get a reliable AR-15.
I went with the high dollar options because I only expect to own one and it's going to be my "civil unrest" gun. So far I appreciate all the suggestions.
 
I went with the high dollar options because I only expect to own one and it's going to be my "civil unrest" gun. So far I appreciate all the suggestions.
Again, you're deluding yourself with marketing jargon BS if you think spending 4x as much as the rest of us pay for a rifle is going to turn you into some kind of shooter. Meanwhile a buddy of mine was dinging steel at over 800 yards yesterday with his rifle that has an $80 barrel and shoots 5 shots into about .8" at 100 yards on the regular.

This is not ARFCOM.
 
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Form, fit, function might cost a little more. What you're paying for is a better machined part, surfaces mating up better, less slop. But sure, there's a limit where you're drinking the coolaid and not getting a better FFF.
 
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I would highly suggest you buy a known quality rifle or at least a quality upper. HM defense sells some good ones that are work horses for around $750.00 or so I think. There's several really reputable brands that have been named ITT, and that's what I'd recommend for your first. You can always drop a trigger in it or put a different stock on it later. Reliability being important, I would definitely not build your first ar and have that as your only one.
 
If you're building for reliability, I would stick to standard components. My built standard AR15 has been totally reliable for the last almost 20 years.

If you're building a standard rifle, all the adjustable (gas block and carrier key) are not really needed unless you're going to run a can and/or different caliber, barrel length. All that adjustability almost begs for mistakes and reliability problems.

The same goes for the PRI gas buster charging handle unless you're going to run a can. Even then BCM charging handles work too.

Only rifles I have adjustable gas blocks (only) on are my AR10's and that's just because they're Creedmoor's and suppressed. Even my AR15 chambered in 6.5 Grendel has a standard gas block and I run it suppresse with no issues. I did put a BCM charging handle on it, but that was for the latch making easier with my optic on it.

Buffers, a standard H2 buffer works fine (since you mentioned a car stock). The JP SCS are nice and I have them on my Creedmoor's and Grendel, but my standard AR carbine is a standard H2.

Trigger is up to what you would like. There's a ton of options. I've had, Geissele (several models), AR Gold, Triggertech, CMC, RRA, KAC, Elftman, LaRue and a couple of others. My standard carbine has a standard trigger. The Creedmoors have a Geissele HSNM which is great and a LaRue MBT (which I plan on getting rid of). The Grendel has an AR Gold which is nice.

Gas tubes. Standard stainless work fine as do melonite.

Barrel, your plans are fine. On my standard I run a Colt barrel.
 
I don’t know anything about AR15’s but want to be ready to build one as soon as California is forced to get rid of their “assault weapons” regulations by the Bruen Decision. My plan is to start accumulating parts now rather than trying to buy them once the rules are changed and 10 million other California gun owners are all trying to buy the same parts I want.

I want a build that I can use for home defense, civil unrest, and training courses I intend to take. I want this gun to be absolutely reliable, but I am not interested in wasting money either. I am looking for a sanity check on my selections (“those two parts don’t work together you moron”) and any feedback on my choices.

Lower – LMT Mars-L (the only part I currently have)

Lower Parts Kit – LMT

Trigger – Hiperfire Hitouch Reflex or Geissele Hi-Speed National Match (DMR springs); The Hiperfire doesn’t have the reputation for reliability like Geissele but I have no experience with two-stage triggers.

Buffer Kit – no idea; does this even matter?

Grip – Magpul MOE K2

Stock – Magpul STR Carbine Stock Mil-Spec

Upper – BCM Mk2 or Vltor MUR; the BCM seems like it’s the new hotness, but it appears that BCM doesn’t sell these to the general public anymore. Is it worth waiting and hoping or just go for it and buy a Vltor when I can find it?

Handguard – KAC URX4 or Vseven; I think the KAC is probably bulletproof but am looking at Vseven for weight savings. Are either of these compatible with the BCM upper or will I need something else? I am assuming they work with the Vltor.

Barrel (16 inch) – FN HF, Noveske N4, or Criterion Core. Leaning towards Noveske because the profile and it weighs less than the FN and the Criterion is at least a 6 month wait (I believe that all the barrels are made by FN). Really looking for feedback here as I expect this is where accuracy is made or broken. Is 1.5 MOA a reasonable expectation for accuracy with decent factory ammo or progressively reloaded ammo? If necessary, I have the time to wait while Compass Lake cuts me a SS barrel.

Gas Tube – no idea if this even matters

Gas Block – Vseven titanium; If I go with pinned (and not clamped) will I need to have someone modify my barrel?

Bolt Carrier Group – Bootleg Adjustable Bolt Carrier or Rubber City Armory Standard Mass 5.56 x 45(223) M16 BCG Complete w/ Adjustable Gas Key. I have no idea if one is better or worse than the other. I am looking at these because my hope is that eventually I will be able to use a suppressor but wanted a non-adjustable gas block for reliability.

Charging Handle – PRI M-84 Gasbuster with combat latch

Muzzle Device – Hellfire linear flash suppressor

I will be hitting up the optics forum for help with the optic, mounts, and BUIS. At some point I will also start a thread on things I will need for tools (cleaning, maintenance, etc.).

Thanks for reading this.

You've gotten a lot of good advice so far so I guess I'll repeat a few things and then give you product advice specifically..since Im willing to bet that you will ultimately still buy whatever you have your heart set on.

1. Yes it would make life a lot easier to just buy a pre-built gun. What you're missing in the overall equation is the fact that when you assemble, you become the QC and the one thats ultimately reliable for making it run correctly. You dont know what you dont know.

2. You will at minimum need some tools.. armorer's wrench/castle nut wrench, torque wrench, a punch set, mini brass/rubber hammer, I highly recommend a vice..and a mag block at minimum. Throw in some levels, and an inch pound torque wrench as well if you plan on mounting any optics. Probably a good idea to get a mini propane torch too. I also wouldnt be assembling a single thing without a reaction rod...and some go/no go gauges..but I know guys who have done it with less.

3. You'll need some degree of manual/mechanical skills. I have friends who cant get the roll pin started in a gas block..and would be stumped by that alone. Others who mangled FCGs/Trigger installs by man-handling and forcing shit that didnt fit right because it wasnt being installed correctly (think friction fit). You also need to be able to recognize this situation..which will only come from experience in building, or having someone more experienced show you.

Also, you'll lack a second, well known, running rifle to quickly grab parts from to test a potentially out of spec BCG, or similar. This is critical. Once again, you dont know what you dont know.

now..beyond that..I think you have overpriced your budget for this first one, and mismatched a lot of parts based on fragmented (and brand fanboy) advice you've collected between ar15.com, reddit, and who knows where fuck else.

So here's my analysis on your parts, and keep in mind the advice is worth exactly what you paid for it, but this comes from my trials and errors by now of building first hand (or assisting others) with close to 2 dozen rifles. Im sure for many thats not much either, but its where Im sharing advice from either way.


Lower – LMT Mars-L (the only part I currently have)

Lower Parts Kit – LMT

Your lower is not compatible with all off the shelf stripped uppers and fully assembled ones as well. here's a good list I found for you to review:



I would probably sell that to some LMT fanboy, and buy a standard milspec lower. Aero enhanced is my recommendation to everyone to start with but I believe there's other similar options, for more money. The enhanced are better than the standard milspec ones with a built in trigger guard (an easy part to break when you install a trigger guard onto a milspec standard AR Lower) and a threaded pin instead of a milspec install with a roll pin for the bolt catch..which normally requires a thin punch and is overall a waste of time. Worth it for those items alone. You can even buy a ballistic advantage enhanced lower now for like $60 and it is identical to the aero in every way, minus the rollmark.

Either way dont waste extra money on a lower, its only a vessel, and as long as the parts fit in it, it will function fine.

Lower parts kit - buy whatever you want, these parts are the cheapest components and more or less meaningless. It might be easier to get one where the baggies are individually marked for each spring and detent and pin. I believe CMMG still does that? Plenty of others do as well. Dont overpay for this.

At minimum, get yourself a document that shows true to size comparisons of each detent, spring, etc. that will help in assembly.

Trigger – Hiperfire Hitouch Reflex or Geissele Hi-Speed National Match (DMR springs); The Hiperfire doesn’t have the reputation for reliability like Geissele but I have no experience with two-stage triggers.

Dont buy gaming/competition or super lightweight triggers if you intend to do home defense, CQB, SHTF or similar. Get a "combat" style trigger. You dont want a twitchy trigger or something super light weight. A good 2 stage will let you "preload" and then have a clean break for the pull. These cover that requirement.

Geissele SSA (not ssa-e) or the SSA's cheaper version- the G2S. You can try their flat bow or similar versions as well, thats 100% strictly shooter preference, regardless of what anyone tells you. Hold out for deals on these. They can be had as cheap as $140 for the G2S or $160ish for The SSA.

Buffer Kit – no idea; does this even matter?
Yes. Matters a lot. Your rifle wont run reliably if you fuck this up. There was years of people testing weights, and springs, and other combos, then VLTOR came out with the A5 kit and basically ended the conversation. buy the RE A5 Receiver extension, and the buffer spring and weight kit. They can sometimes be found as 1 package, sometimes you gotta buy them separately. This will save you a TON of headaches. Dont get into any spring upgrades or weight..you DONT need them yet. The majority of rifles will run perfectly fine with the standard vltor a5 weight and spring.


Upper – BCM Mk2 or Vltor MUR; the BCM seems like it’s the new hotness, but it appears that BCM doesn’t sell these to the general public anymore. Is it worth waiting and hoping or just go for it and buy a Vltor when I can find it?

As mentioned previously, if you stick with LMT, you will need an LMT compatible upper. If you decide to get a standard lower instead (milspec or enhanced) pick up a similar option them. If you're set on BCM (based on arfcom or reddit advice), just buy an assembled upper (barrel and handguard/rail included) and skip the next steps. This will save you a lot of trouble shooting, time, and money.


Barrel (16 inch) – FN HF, Noveske N4, or Criterion Core. Leaning towards Noveske because the profile and it weighs less than the FN and the Criterion is at least a 6 month wait (I believe that all the barrels are made by FN). Really looking for feedback here as I expect this is where accuracy is made or broken. Is 1.5 MOA a reasonable expectation for accuracy with decent factory ammo or progressively reloaded ammo? If necessary, I have the time to wait while Compass Lake cuts me a SS barrel.


You're all over the place on barrels, to be honest with you, so time to reel you in.. You have no clue what you want or need (yet) to look to compass lake to custom cut you anything.

FN and Criterion can both be found online at various places. Sometimes you get a backorder, sometimes its ready to buy. Another good option for the money and what you're looking to do is https://www.lothar-walther.com/. They were in the sub $300 price range last time I had them quote me an off the shelf barrel.

You can reasonably expect below 1.5 MOA accuracy with any decent barrel. If you want 1.5 MOA..buy some budget grade ballistic advantage hanson barrel.

As far as accuracy being made or broken..thats likely going to depend on ammo and you more than the barrel. Can you even shoot Sub MOA with an AR? standing? Prone? Bipod or sandbags? ETC. Any money saved from your original budget should be spent on ammo and training to shoot sub moa in the first place.

Criterion Cores can be had for $250 with discounts from many shops..you just have to wait to snag one in stock. Aside from that, I'd look hard at Lothar Walther. All the other options you mention are likely going to be above $400, unless you buy a PSA FN made barrel, and even then, quality and qc from PSA can be hit or miss. I dont think you need a $400 (or more) barrel at this point. Thats honest advice and you REALLY should consider that above all else. Barrels are consumables and you still can buy multiple ones or replace it. If you're gonna blow your wad on one, buy something Bartlein made from Frank Greene..if you read all the contributions he makes to the forum regularly you'll see why.



Gas Tube – no idea if this even matters - not really, just get the right profile based no your barrel, from just about anyone.

Gas Block – Vseven titanium; If I go with pinned (and not clamped) will I need to have someone modify my barrel?

If you're gonna spend this much on a gas block, go with a superlative arms adjustable one. That makes even more sense if you plan on ever going suppressed. I like these so much I put them on every rifle now. It helps with tuning gas to get a smoother rifle and avoid premature wear on components. If you use a set-screw style gas block instead of a clamp on, you'll need to dimple the barrel. its pretty easy to do if you're comfortable with a drill. If not, pay someone to do so.

Bolt Carrier Group – Bootleg Adjustable Bolt Carrier or Rubber City Armory Standard Mass 5.56 x 45(223) M16 BCG Complete w/ Adjustable Gas Key. I have no idea if one is better or worse than the other. I am looking at these because my hope is that eventually I will be able to use a suppressor but wanted a non-adjustable gas block for reliability

The world is your oyster on these..I wouldnt get anything adjustable at this point, just get something that has properly staked gas screws and good quality components. I hear microbest makes the bulk of them out there, including for popular brands like SOLGW. A Microbest branded one is like $100..A chrome one is $150 ish. You can find the Centurion C4 or the SOLGW one for below $150 and those will be quality BCGs you wont have to second guess, with brands that stand behind their warranty.


Grip – Magpul MOE K2
Dont get hung up on this. you will likely try a few until you get the right one. However, an MOE k2 is angled a little more for shorter stuff/PDWs, so I would start with an MOE instead.

Stock – Magpul STR Carbine Stock Mil-Spec
I think these are like flavors of ice cream..everyone has their own favorites. My personal one to run on a combat style rifle and recommend to everyone is VLTOR IMOD. Get the standard spec. Clubfoot is mostly for kitted up use..think plate carrier and whatever else on your chest.

Charging Handle – PRI M-84 Gasbuster with combat latch
Pointless to get a gasbuster unless you're already running a suppressor. Get a Radian if you want "gucci" or some flavor of Aero radian.. The Aero Ambi with extra large hooks are nice. Especially for gloved hands. Otherwise just get a milspec one to save yourself some money.

Muzzle Device – Hellfire linear flash suppressor
You probably dont need that. Muzzle device will change if you run suppressors, in the mean time..a VG6 or a precision armament M4-72 if you're looking for "flatter shooting" or recoil reduction. No muzzle devices help with noise other than suppressors.

good data in some of these on muzzle devices:

Good luck, continue to ask plenty of questions.
 
You've gotten a lot of good advice so far so I guess I'll repeat a few things and then give you product advice specifically..since Im willing to bet that you will ultimately still buy whatever you have your heart set on.

1. Yes it would make life a lot easier to just buy a pre-built gun. What you're missing in the overall equation is the fact that when you assemble, you become the QC and the one thats ultimately reliable for making it run correctly. You dont know what you dont know.

2. You will at minimum need some tools.. armorer's wrench/castle nut wrench, torque wrench, a punch set, mini brass/rubber hammer, I highly recommend a vice..and a mag block at minimum. Throw in some levels, and an inch pound torque wrench as well if you plan on mounting any optics. Probably a good idea to get a mini propane torch too. I also wouldnt be assembling a single thing without a reaction rod...and some go/no go gauges..but I know guys who have done it with less.

3. You'll need some degree of manual/mechanical skills. I have friends who cant get the roll pin started in a gas block..and would be stumped by that alone. Others who mangled FCGs/Trigger installs by man-handling and forcing shit that didnt fit right because it wasnt being installed correctly (think friction fit). You also need to be able to recognize this situation..which will only come from experience in building, or having someone more experienced show you.

Also, you'll lack a second, well known, running rifle to quickly grab parts from to test a potentially out of spec BCG, or similar. This is critical. Once again, you dont know what you dont know.

now..beyond that..I think you have overpriced your budget for this first one, and mismatched a lot of parts based on fragmented (and brand fanboy) advice you've collected between ar15.com, reddit, and who knows where fuck else.

So here's my analysis on your parts, and keep in mind the advice is worth exactly what you paid for it, but this comes from my trials and errors by now of building first hand (or assisting others) with close to 2 dozen rifles. Im sure for many thats not much either, but its where Im sharing advice from either way.


Lower – LMT Mars-L (the only part I currently have)

Lower Parts Kit – LMT

Your lower is not compatible with all off the shelf stripped uppers and fully assembled ones as well. here's a good list I found for you to review:



I would probably sell that to some LMT fanboy, and buy a standard milspec lower. Aero enhanced is my recommendation to everyone to start with but I believe there's other similar options, for more money. The enhanced are better than the standard milspec ones with a built in trigger guard (an easy part to break when you install a trigger guard onto a milspec standard AR Lower) and a threaded pin instead of a milspec install with a roll pin for the bolt catch..which normally requires a thin punch and is overall a waste of time. Worth it for those items alone. You can even buy a ballistic advantage enhanced lower now for like $60 and it is identical to the aero in every way, minus the rollmark.

Either way dont waste extra money on a lower, its only a vessel, and as long as the parts fit in it, it will function fine.

Lower parts kit - buy whatever you want, these parts are the cheapest components and more or less meaningless. It might be easier to get one where the baggies are individually marked for each spring and detent and pin. I believe CMMG still does that? Plenty of others do as well. Dont overpay for this.

At minimum, get yourself a document that shows true to size comparisons of each detent, spring, etc. that will help in assembly.

Trigger – Hiperfire Hitouch Reflex or Geissele Hi-Speed National Match (DMR springs); The Hiperfire doesn’t have the reputation for reliability like Geissele but I have no experience with two-stage triggers.

Dont buy gaming/competition or super lightweight triggers if you intend to do home defense, CQB, SHTF or similar. Get a "combat" style trigger. You dont want a twitchy trigger or something super light weight. A good 2 stage will let you "preload" and then have a clean break for the pull. These cover that requirement.

Geissele SSA (not ssa-e) or the SSA's cheaper version- the G2S. You can try their flat bow or similar versions as well, thats 100% strictly shooter preference, regardless of what anyone tells you. Hold out for deals on these. They can be had as cheap as $140 for the G2S or $160ish for The SSA.

Buffer Kit – no idea; does this even matter?
Yes. Matters a lot. Your rifle wont run reliably if you fuck this up. There was years of people testing weights, and springs, and other combos, then VLTOR came out with the A5 kit and basically ended the conversation. buy the RE A5 Receiver extension, and the buffer spring and weight kit. They can sometimes be found as 1 package, sometimes you gotta buy them separately. This will save you a TON of headaches. Dont get into any spring upgrades or weight..you DONT need them yet. The majority of rifles will run perfectly fine with the standard vltor a5 weight and spring.


Upper – BCM Mk2 or Vltor MUR; the BCM seems like it’s the new hotness, but it appears that BCM doesn’t sell these to the general public anymore. Is it worth waiting and hoping or just go for it and buy a Vltor when I can find it?

As mentioned previously, if you stick with LMT, you will need an LMT compatible upper. If you decide to get a standard lower instead (milspec or enhanced) pick up a similar option them. If you're set on BCM (based on arfcom or reddit advice), just buy an assembled upper (barrel and handguard/rail included) and skip the next steps. This will save you a lot of trouble shooting, time, and money.


Barrel (16 inch) – FN HF, Noveske N4, or Criterion Core. Leaning towards Noveske because the profile and it weighs less than the FN and the Criterion is at least a 6 month wait (I believe that all the barrels are made by FN). Really looking for feedback here as I expect this is where accuracy is made or broken. Is 1.5 MOA a reasonable expectation for accuracy with decent factory ammo or progressively reloaded ammo? If necessary, I have the time to wait while Compass Lake cuts me a SS barrel.


You're all over the place on barrels, to be honest with you, so time to reel you in.. You have no clue what you want or need (yet) to look to compass lake to custom cut you anything.

FN and Criterion can both be found online at various places. Sometimes you get a backorder, sometimes its ready to buy. Another good option for the money and what you're looking to do is https://www.lothar-walther.com/. They were in the sub $300 price range last time I had them quote me an off the shelf barrel.

You can reasonably expect below 1.5 MOA accuracy with any decent barrel. If you want 1.5 MOA..buy some budget grade ballistic advantage hanson barrel.

As far as accuracy being made or broken..thats likely going to depend on ammo and you more than the barrel. Can you even shoot Sub MOA with an AR? standing? Prone? Bipod or sandbags? ETC. Any money saved from your original budget should be spent on ammo and training to shoot sub moa in the first place.

Criterion Cores can be had for $250 with discounts from many shops..you just have to wait to snag one in stock. Aside from that, I'd look hard at Lothar Walther. All the other options you mention are likely going to be above $400, unless you buy a PSA FN made barrel, and even then, quality and qc from PSA can be hit or miss. I dont think you need a $400 (or more) barrel at this point. Thats honest advice and you REALLY should consider that above all else. Barrels are consumables and you still can buy multiple ones or replace it. If you're gonna blow your wad on one, buy something Bartlein made from Frank Greene..if you read all the contributions he makes to the forum regularly you'll see why.



Gas Tube – no idea if this even matters - not really, just get the right profile based no your barrel, from just about anyone.

Gas Block – Vseven titanium; If I go with pinned (and not clamped) will I need to have someone modify my barrel?

If you're gonna spend this much on a gas block, go with a superlative arms adjustable one. That makes even more sense if you plan on ever going suppressed. I like these so much I put them on every rifle now. It helps with tuning gas to get a smoother rifle and avoid premature wear on components. If you use a set-screw style gas block instead of a clamp on, you'll need to dimple the barrel. its pretty easy to do if you're comfortable with a drill. If not, pay someone to do so.

Bolt Carrier Group – Bootleg Adjustable Bolt Carrier or Rubber City Armory Standard Mass 5.56 x 45(223) M16 BCG Complete w/ Adjustable Gas Key. I have no idea if one is better or worse than the other. I am looking at these because my hope is that eventually I will be able to use a suppressor but wanted a non-adjustable gas block for reliability

The world is your oyster on these..I wouldnt get anything adjustable at this point, just get something that has properly staked gas screws and good quality components. I hear microbest makes the bulk of them out there, including for popular brands like SOLGW. A Microbest branded one is like $100..A chrome one is $150 ish. You can find the Centurion C4 or the SOLGW one for below $150 and those will be quality BCGs you wont have to second guess, with brands that stand behind their warranty.


Grip – Magpul MOE K2
Dont get hung up on this. you will likely try a few until you get the right one. However, an MOE k2 is angled a little more for shorter stuff/PDWs, so I would start with an MOE instead.

Stock – Magpul STR Carbine Stock Mil-Spec
I think these are like flavors of ice cream..everyone has their own favorites. My personal one to run on a combat style rifle and recommend to everyone is VLTOR IMOD. Get the standard spec. Clubfoot is mostly for kitted up use..think plate carrier and whatever else on your chest.

Charging Handle – PRI M-84 Gasbuster with combat latch
Pointless to get a gasbuster unless you're already running a suppressor. Get a Radian if you want "gucci" or some flavor of Aero radian.. The Aero Ambi with extra large hooks are nice. Especially for gloved hands. Otherwise just get a milspec one to save yourself some money.

Muzzle Device – Hellfire linear flash suppressor
You probably dont need that. Muzzle device will change if you run suppressors, in the mean time..a VG6 or a precision armament M4-72 if you're looking for "flatter shooting" or recoil reduction. No muzzle devices help with noise other than suppressors.

good data in some of these on muzzle devices:

Good luck, continue to ask plenty of questions.

Thanks for taking the time to type that out; it's fantastic. Much appreciated.
 
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