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Does the AR upper receiver matter?

Smoketheclay

Private
Minuteman
Dec 28, 2017
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I’m looking to do a few upper builds, with top tier handguards, and Krieger barrels.

Assuming the upper receiver is mil spec, from Anderson to Noveske/BCM - will the upper receiver matter for group size or anything else?
 
Doubtful.... Depends on your budget. I'd research more on the barrels than the receiver. At this point of the game, actually getting your hands on parts for a build could be the deciding factor. If you are in no hurry you can get on the waiting list for top shelf products...
Budget and time frame to complete builds are big factors right now.

Hobo
 
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All mil spec means is that they follow guidelines with materials and tolerance so all parts can interchange with little variance so that the rifle will run. if you are investing in a nice barrel, pay for quality parts with good QC.
 
Interface with the barrel extension, followed by fit to the lower (including tightness/slop in the pins) are the most important aspects of an upper receiver for a precision build. Mil-spec isn’t necessarily the issue, it’s how well they fit. I have a sub moa AR with an Anderson sport slick side upper and another one with an Odin billet upper; both have been fitted to their barrel extensions and lowers.
 
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I’d lay more importance fit between the barrel extension and upper vs brand. Especially with forged offerings. A Noveske Gen 1 recently treated me well in this regard. It’s a good feeling when a few taps are needed to mate the two.

Send your upper to whoever is cutting the barrels and they can get you the best possible fit with varying extension ODs.
 
How tight the upper fits the barrel extension 100% affect accuracy. Think of it as the more wobbles (play) the barrel has, the more this wobbles affect the barrel harmonic.

I hear people say that they can just tightens the barrel nut more. No, you can't just tightened the barrel nut more because the barrel nut need to be indexed on your gas tube.

Bottom line, the tighter your barrel extension fits in the upper reciever, the more repeatable your shots will be.

From my experience, a couple of upper receiver have really tight tolerance and good for precision build: BCM, Noveske Gen1, Mega forge.
 
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So a question from no experience, where do the different name brands stack up? I can get Palmetto State and Aero Precision components. Are there the Walmart versions of the pool?
 
So a question from no experience, where do the different name brands stack up? I can get Palmetto State and Aero Precision components. Are there the Walmart versions of the pool?
The first thing to be aware of is forging quality and material. A common aphorism is that there are only a few forges; that may be true, but final machining is very important and this is where you’ll see divergence between brands. Different specs in tolerance, finishing/coating, down to actual machinery used all will make a difference.

Well known names I don’t trust QA/QC practices of: PSA, Anderson, Aero, Strike.

Small names I don’t trust QA/QC practices of: All of them unless otherwise mentioned because it’s all subcontracted out to God knows who and at God knows what specs. There’s lots of private labeling and rebranding going on in this space.

Some names I trust and own: Centurion, VLTOR, BCM, KAC, MEGA (now ZEV).

Some names I’ve been told to trust, but don’t own: SOLGW, Sionics, LMT, FN, Colt.
 
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So a question from no experience, where do the different name brands stack up? I can get Palmetto State and Aero Precision components. Are there the Walmart versions of the pool?

All the $69 uppers are pretty much the same quality.

I would considered the Aero Precision forge upper a "Wal-Mart" version. It's tolerance is some what tighter than the rest of the cheapo, barely suitable for a precision build. However, if you can afford $75 for an Aero forge upper, you'd be much more happy if you get a BCM blem upper for about $90 shipped.
 
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For all out precision I'll second the VLTOR MUR. Next would be the old MEGA now owned by ZEV. Both of those uppers have a tighter bore and will be a tighter fit to most barrel extensions.
 
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For all out precision I'll second the VLTOR MUR. Next would be the old MEGA now owned by ZEV. Both of those uppers have a tighter bore and will be a tighter fit to most barrel extensions.
I forgot to mention the now deceased MEGA which lives on as ZEV. If you look around there are still places with stock of private labeled MEGA/ZEV receivers.
 
For all out precision I'll second the VLTOR MUR. Next would be the old MEGA now owned by ZEV. Both of those uppers have a tighter bore and will be a tighter fit to most barrel extensions.

It depends on the individual part and your individual barrel though. I swapped out a Mega upper several years ago for the aforementioned random Anderson because that specific example fit my barrel extension tighter than the Mega did. It really is an individual part-by-part thing, rather than just a blanket “these makes rock and these makes suck” thing. Believe me, nothing feels weirder than tossing your $180 upper into the parts bin for a $40 slick side Anderson, ha.
 
It depends on the individual part and your individual barrel though. I swapped out a Mega upper several years ago for the aforementioned random Anderson because that specific example fit my barrel extension tighter than the Mega did. It really is an individual part-by-part thing, rather than just a blanket “these makes rock and these makes suck” thing. Believe me, nothing feels weirder than tossing your $180 upper into the parts bin for a $40 slick side Anderson, ha.
You know what feels worse? Buying a V7 slickside upper and realizing it’s just an Anderson with the rails machined.
 
For all out precision I'll second the VLTOR MUR. Next would be the old MEGA now owned by ZEV. Both of those uppers have a tighter bore and will be a tighter fit to most barrel extensions.

So is the "new" ZEV forged upper really the same as the "old" Mega?

As with most decent uppers right now, the ZEV stuff is un-obtainium as well?

What about the Lantac forged uppers? Any good, or just another face?

MM
 
So is the "new" ZEV forged upper really the same as the "old" Mega?

As with most decent uppers right now, the ZEV stuff is un-obtainium as well?

What about the Lantac forged uppers? Any good, or just another face?

MM

The Lantac billet are good to go (I have 6 of them now). No idea about the forged but at 8-ish ounces stripped and cut to work with any handguard, the current gen of Lantac Billets are now my go-to.
 
So is the "new" ZEV forged upper really the same as the "old" Mega?

As with most decent uppers right now, the ZEV stuff is un-obtainium as well?

What about the Lantac forged uppers? Any good, or just another face?

MM
From what I have seen yes. I believe the reason the bore is small diameter is because they were teflon coating them.
I think every AR part is hard to find right now. I have had to change suppliers(wholesale) that I have been using for 12 years.
Sorry I don't know about the Lantac, never had my hands on one.
 
Thanks everyone for the info, I’ve learned a lot from the discussion. Some follow up questions/discussions:

I have for the build:
Spikes lower (I can’t change this because I live in CA)
Noveske handguard
Ordering a Krieger barrel with barrel extension included

After reading through the above, am I better off getting:
Spikes upper (to match the lower)?
Noveske gen 1 upper to match the handguard?
Other?
 
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Don’t worry about matching the rail, and the Spikes won’t necessarily match the lower (my first build was a Spikes, gets me all warm and fuzzy). Honestly, for a precision build the best advice is to get to know a smith well who can fit the parts together well through some fitting work and/or buy a couple and see which is the best fitting out of the box with your barrel and lower.
 
naw dont matter, extra weight...just popit off and mail it to me for proper burial.
 
When I lived in Florida I had access to bins of spikes receivers, so I could mix and match until I found good fits. I generally build off matched receiver sets, short list is vltor and mega. If your barrel isn’t snug in the receiver extension, you can use machining shims and green loctite to snug things up.
 
Thanks everyone for the info, I’ve learned a lot from the discussion. Some follow up questions/discussions:

I have for the build:
Spikes lower (I can’t change this because I live in CA)
Noveske handguard
Ordering a Krieger barrel with barrel extension included

After reading through the above, am I better off getting:
Spikes upper (to match the lower)?
Noveske gen 1 upper to match the handguard?
Other?


You should get the BCM blem Upper that several people recommended you get...
 
Thanks everyone for the info, I’ve learned a lot from the discussion. Some follow up questions/discussions:

I have for the build:
Spikes lower (I can’t change this because I live in CA)
Noveske handguard
Ordering a Krieger barrel with barrel extension included

After reading through the above, am I better off getting:
Spikes upper (to match the lower)?
Noveske gen 1 upper to match the handguard?
Other?

Noveske gen1 upper for sure. If you can't find a Noveske gen1 then get a BCM blem upper from their website.
 
I would go with Vltor MUR or BCM. The Vltor is known to be a more rigid upper which Is good for accuracy.
 
I haven't heard the Seekins IRMT uppers mentioned... I have no experience but aren't those basically like the Vltor MUR but a two piece instead of all one unit?

Any one use those and like them better than the standard upper/barrel interface?
 
I haven't heard the Seekins IRMT uppers mentioned... I have no experience but aren't those basically like the Vltor MUR but a two piece instead of all one unit?

Any one use those and like them better than the standard upper/barrel interface?
I have four and they're very tight tolerances when matched w/ Seekins parts including the lower. Very accurate w/ 77 gr SMK. The 300 blk is as accurate as it can be with 8" barrel.
 
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I have four and they're very tight tolerances when matched w/ Seekins parts including the lower. Very accurate w/ 77 gr SMK. The 300 blk is as accurate as it can be with 8" barrel.

I really like the look of the Seekins NX15 billet upper, but I cannot find any info about how tight a fit the barrel extension is likely to be.
 
I really like the look of the Seekins NX15 billet upper, but I cannot find any info about how tight a fit the barrel extension is likely to be.
I actually have SP223 billet uppers and they’re tight. I imagine the lighter NX15 would be as well. The whole point to the IRMT is the forearm connects directly to the receiver vs the barrel nut creating a “true” free float barrel and mimicking monolithic accuracy.
 
I would go with Vltor MUR or BCM. The Vltor is known to be a more rigid upper which Is good for accuracy.
They’re not available stripped, but I think the BCM Mk2 forged upper is the best of both worlds here.
You should get the BCM blem Upper that several people recommended you get...
^I guarantee you it’ll fit tighter than a VTLOR MUR, at 1/3 the price too. I love VLTOR MUR uppers, but never has one that’s passed through my hands been even remotely as tight as an undersized BCM.
 
^I guarantee you it’ll fit tighter than a VTLOR MUR, at 1/3 the price too. I love VLTOR MUR uppers, but never has one that’s passed through my hands been even remotely as tight as an undersized BCM.

I agree with this, I shim and thermal fit all my barrels, if you’re not doing that then BCM is the way to go.
 
I use a lapping tool to square up the face of the receiver where the barrel extension meets it, and I use green loctite (the bearing seal stuff) inside the extension receiver area to help make that all a little more squared up amd stout. If I'm going for the most accuracy I try to fit the barrel into the tightest available upper receiver. If you are only buying one and your gun shop is nice like that they might let you test fit you are barrel into the upper receiver before you buy it.
 
Yes. I recently got a "free" flat top upper for postage. Then bought an upper and bolt at the same time, side charge set. Original owner said his bolt bound in the free one. He used all the parts In a different upper with no problem. I'm going to try it with my A2 .22 upper parts. If it doesn't work I have to buy one. I figure the bolt guides in the .22 insert shouldn't care about a tight spot.
 
I use a lapping tool to square up the face of the receiver where the barrel extension meets it, and I use green loctite (the bearing seal stuff) inside the extension receiver area to help make that all a little more squared up and stout. If I'm going for the most accuracy I try to fit the barrel into the tightest available upper receiver. If you are only buying one and your gun shop is nice like that they might let you test fit you are barrel into the upper receiver before you buy it.

This. This x100 for a precision build.
 
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Noveske makes good shit and I've used a lot of their parts over the years. The MUR1 is another really good upper I use. One thing I noticed about "milspec" cheap uppers is that some tend to vary --when I switched to KAC lowers, I noticed some cheaper uppers would leave large gaps in the rear. They'd pin on, but they didn't fit well. The Noveske, MUR1, LMT and I wanna say a BCM upper all fit. I have a Colt upper out there I think will work well too. Oh, an AAC upper will fit too, whatever they used.

A good 7075 forged upper made by a quality company is usually good to go. Part of what you're paying for besides tolerance of the part is the finish they use too. There's a big difference there.

But best bang for buck IMO is the MUR1, wanna say they're 7075. It's a solid part that usually fits well. Noveske used to use those a lot until they started making their own version and they tend to fit Noveske lowers very well FWIW. I don't know if it helps having a beefier upper like that, it does make me feel better about the Grendels I guess, but it's a good upper overall regardless and I don't think it's that much heavier over a typical forged upper.

As far as accuracy goes, I've taken to facing the upper with a lapping tool, it's easy enough to do. I've noticed most of the quality uppers are already pretty flat. Then Loctite 620 to bed the barrel to the upper. It's a permanent installation, meaning a barrel change includes a new upper receiver, but it makes it makes the whole thing solid.

Not an upper, but the KAC URX4 handguard is a one piece unit that can torque on higher than regular barrel nuts. Being one piece and tight like that, it basically makes a bedded upper into a monolithic piece for all practical purposes. I haven't found anything better.
 
Noveske makes good shit and I've used a lot of their parts over the years. The MUR1 is another really good upper I use. One thing I noticed about "milspec" cheap uppers is that some tend to vary --when I switched to KAC lowers, I noticed some cheaper uppers would leave large gaps in the rear. They'd pin on, but they didn't fit well. The Noveske, MUR1, LMT and I wanna say a BCM upper all fit. I have a Colt upper out there I think will work well too. Oh, an AAC upper will fit too, whatever they used.

A good 7075 forged upper made by a quality company is usually good to go. Part of what you're paying for besides tolerance of the part is the finish they use too. There's a big difference there.

But best bang for buck IMO is the MUR1, wanna say they're 7075. It's a solid part that usually fits well. Noveske used to use those a lot until they started making their own version and they tend to fit Noveske lowers very well FWIW. I don't know if it helps having a beefier upper like that, it does make me feel better about the Grendels I guess, but it's a good upper overall regardless and I don't think it's that much heavier over a typical forged upper.

As far as accuracy goes, I've taken to facing the upper with a lapping tool, it's easy enough to do. I've noticed most of the quality uppers are already pretty flat. Then Loctite 620 to bed the barrel to the upper. It's a permanent installation, meaning a barrel change includes a new upper receiver, but it makes it makes the whole thing solid.

Not an upper, but the KAC URX4 handguard is a one piece unit that can torque on higher than regular barrel nuts. Being one piece and tight like that, it basically makes a bedded upper into a monolithic piece for all practical purposes. I haven't found anything better.


All of this. A high quality upper is expensive because of QC. You're paying for that meticulous consistency which cost a lot of money on a mass produced product.

The variation of tolerance of different manufacturers is too vast: barrel extension vs. Upper Inner diameter.

From my experience, permanent bedding works better than shim. When I bedded my AR barrel, I'd see random "consistency" of upper inner diameter. Sometime they're tight in the front toward index pin. Sometime they're tight toward the back toward feed ramp.

The last time I bought a Noveske Gen1 upper was when John was still alive. Not sure about their quality now. I'd assume that it's still good to go.

If you have a Noveske rail then I would get a matching Noveske upper. It costs may be $20 more than the new BCM upper. Choose which roll mark you prefers.

Either way, you wont be disappointed. Lots of good recommendation in this thread.
 
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Not an upper, but the KAC URX4 handguard is a one piece unit that can torque on higher than regular barrel nuts. Being one piece and tight like that, it basically makes a bedded upper into a monolithic piece for all practical purposes. I haven't found anything better.
Hah funny story/coincidence: I JUST built an upper with a VLTOR MUR and URX4.
 
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In addition to the upper receiver to barrel fit, barrel torque and contour also come into play. I cannot for the life of me find the youtube video where one of the premier barrel manufacturers was saying that for a bull barrel 47 ft/lbs is ideal, and to increase torque by 5 ft/lbs until optimal accuracy is achieved. 60 ft/lbs for gov't profile I believe.

I just remember that because the torque specifications were so specific as a starting point.
 
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If you feel the top tier Upper is affordable, you should buy it and build on it with no hesitation.

Otherwise, squaring the receiver face, and bedding the barrel extension are good ideas. Neither is necessary to proper function; but many (myself included) consider it beneficial to accuracy.

Squaring can be done at home prior to assembly; a kit is utilized in conjunction with a hand drill, lower speed is better. I use standard coarse valve grinding compound as my abrasive, and I clean it up thoroughly afterward.

Barrel extension bedding is typically described as using Permanent (Red) Loc-Tite. I've done both of these processes, and had no problems in the process. I allowed the assembly to cure overnight. There are several varieties of Red Loc-Tite; and I assume someone will be along eventually to add that info after my post.

I performed the barrel nut seating three times to peen in the receiver threads. The nut I used had a hex profile, and I used a crowfoot wrench attachment on my ancient automotive Torque wrench to attain a final torque of 60 Ft Lb. The nut was lubed with anti-seize compound.

I was troubled by the idea that the permanent Loc-Tite would prevent me from removing the barrel. I haven't tried it and likely won't. But I also concluded that there might be an option here.

If I do this again, I will start by applying release agent to the barrel extension where it would come in content with the Loc-Tite. Let it dry completely before proceeding further. It may have no effect beyond allaying my unnecessary caution.

These were my base components, 15".

Greg
 
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Along these lines, I am building a precision upper. I have two choices for receiver. One is a vltor that I previously used, but has less than 100 rounds, and the other is a new colt. I have the tools to square up and bedding compound, but which of the two is a better choice for this build?
 
Along these lines, I am building a precision upper. I have two choices for receiver. One is a vltor that I previously used, but has less than 100 rounds, and the other is a new colt. I have the tools to square up and bedding compound, but which of the two is a better choice for this build?
Check the barrel extension fit and pick the tighter one.
 
I think it's interesting that 2 guys who build some of the most accurate uppers on the planet, use a basic $100, plain jane, mi-spec upper..............Frank White at Compass Lake & John Holliger at White Oak.

And then someone like John Paul of JP rifles uses a $350 proprietary billet upper.

Go figure...............................

MM
 
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I think it's interesting that 2 guys who build some of the most accurate uppers on the planet, use a basic $100, plain jane, mi-spec upper..............Frank White at Compass Lake & John Holliger at White Oak.

And then someone like John Paul of JP rifles uses a $350 proprietary billet upper.

Go figure...............................

MM

If they were available, I’d be using BCM Mk2 receivers.
 
They’re not available stripped, but I think the BCM Mk2 forged upper is the best of both worlds here.

^I guarantee you it’ll fit tighter than a VTLOR MUR, at 1/3 the price too. I love VLTOR MUR uppers, but never has one that’s passed through my hands been even remotely as tight as an undersized BCM.
There are a number of rail systems including some of the best like gisessle that will not work with the mk2.

BCM makes the best forged uppers. Hands down no question. 95% is the quality of machining and consistency. It’s a staple of many precision Builds and unless you are hanging a giant barrel, the added stiffness of billet is Not worth it. A forging will always be a stronger receiver, all things being equal.
 
Just have Precision Firearms do the upper builds for you.

That guy does shit work and is an ass. My opinion is from 1 hand experience back around 2012. Hard pass.

Krieger
Proof research
Compass lake
All make top notch barrels.


Back to the original question no and I've used a wide assortment from mega arms monolithic to cheap Andersons. My favorite these days is Aero Precision.

I always use full length buffers in my precision builds and adjustable gas blocks.

The barrel is the deciding component and I've owned several 1/2 and 3/4 moa ar15 and ar10's.