Help with AR 308 build

B Man

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Want experienced advice on this build. I’m going to have CLE spin me a 20” fluted bartlein barrel in 308 win and match the bolt to it. This will be a hunting and precision build so I want to ride the fence on weight and maneuverability.

I’m going to go with an Aero M5 Enhanced or Seekins SP10 matched builders kit. Opinions?

For the BCG he carries and builds using Aero which must means it’s a great bolt. But should I get a Tool Craft or Rubber City Armory instead? Price on the tool craft is great for the reputation it carry’s.

Rifle will have a full length buffer tube. What spring and weight do you recommend. Standard Aero or something better and why please? I want simple and durable. I will be running an adjustable gas block on it.
 

rpoL98

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I recommend getting a BCG where the rear of the fat end of the carrier is beveled. Helps to prevent damage to the lower rcvr buffer-tube upright in inadvertent adverse situations where the BCG overtravels, due to whatever unintended reasons (spring, buffer too short/light, over-gassed, etc).

utgjdfN.jpg


SE5sylF.jpg
 
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n2ishun

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    Aero BCG is a toolcraft.
    Ballistic Advantage (which is owned by Aero) is a toolcraft.
    I bought a Ballistic BCG for a 308a few months ago for $129.
    I haven't seen a better deal in years.....keep an eye on both BA and Aero, occasionally they have some spanky deals.
     

    B Man

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    So I see a site has the Tool Craft BCG’s both single ejector and double ejector on sale for $110. Double ejector bcg has the small firing pin hole. Any issues with this and which to get? Precision and reliability in mind.
     

    rpoL98

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    Aero BCG is a toolcraft.
    Ballistic Advantage (which is owned by Aero) is a toolcraft.
    I bought a Ballistic BCG for a 308a few months ago for $129.
    I haven't seen a better deal in years.....keep an eye on both BA and Aero, occasionally they have some spanky deals.
    AFAIK, Aero BCG is not Toolcraft. Aero 308 BCG has the chamfered rear of the fat part of the bolt carrier, Toolcraft has the squared-off sharp edges which impact the lower receiver upright and leave marks.

    Aero nitride 308 BCG has the small HP firing pin, bolt-face firing pin aperture, well suited for 6.5CM, and not a bad thing for 308 either.

    the Brownells nitride 308 BCG also has the rounded butt-end of the fat part of the 308 bolt carrier (and the HP firing pin set-up), at a much reduced cost, last time I checked it was about $140.

    AFAIK, there isn't a nitrided DPMS-pattern 308 BCG that has the chamfered fat end of the carrier, and dual ejectors, and HP firing pin/aperture.
     

    B Man

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    AFAIK, Aero BCG is not Toolcraft. Aero 308 BCG has the chamfered rear of the fat part of the bolt carrier, Toolcraft has the squared-off sharp edges which impact the lower receiver upright and leave marks.

    Aero nitride 308 BCG has the small HP firing pin, bolt-face firing pin aperture, well suited for 6.5CM, and not a bad thing for 308 either.

    the Brownells nitride 308 BCG also has the rounded butt-end of the fat part of the 308 bolt carrier (and the HP firing pin set-up), at a much reduced cost, last time I checked it was about $140.

    AFAIK, there isn't a nitrided DPMS-pattern 308 BCG that has the chamfered fat end of the carrier, and dual ejectors, and HP firing pin/aperture.
    So you are saying the Aero is a better bolt than the Toolcraft for my application?
     

    rpoL98

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    if the lower receiver you are using has these red-circled notches, then you should be fine with a squared fat-end 308 bolt carrier.

    Hg1UHm9.png
     

    B Man

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    I recommend getting a BCG where the rear of the fat end of the carrier is beveled. Helps to prevent damage to the lower rcvr buffer-tube upright in inadvertent adverse situations where the BCG overtravels, due to whatever unintended reasons (spring, buffer too short/light, over-gassed, etc).

    utgjdfN.jpg


    SE5sylF.jpg
    if the lower receiver you are using has these red-circled notches, then you should be fine with a squared fat-end 308 bolt carrier.

    Hg1UHm9.png
    The aero lower doesn’t have those notches looking at them online. And the Toolcraft bcg looks like it has the squared notch not like the Aero bcg that is slanted…. So guess Aero it is…. That’s what Compass Lake uses anyhow is Aero bcg’s so I may just let him add a BCG with the barrel.
     

    Bigtrucknut

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    I use AP receivers and BCGs exclusively and then may install a Rubber City bolt if offered with a custom barrel. I've never needed a dual ejector bolt. Bevel on the BCG is irrelevant if your buffer, spring, and buffer tube are correct/matched. Always test the buffer, tube length, spring, and BCG for compatibility before firing. With the spring removed, buffer should bottom out in the buffer tube with enough room to accommodate the BCG before it bottoms out in the receiver. Then install the spring and force the BCG into the buffer tube again - it should bottom out to the same distance that it did without the spring. If it doesn't go in as far then the spring is too long and is getting coil stacked. Fix. Mixing Armalite and DPMS buffer system parts can be a problem so I recommend this simple test just to make sure.

    As far as spring, buffer weight, and adjustable gas block - I like a heavy buffer (9-10 oz), lighter buffer spring rate, and reduced gas. Heavier buffer and reduced gas increase bolt lock up time and minimize felt recoil while the light(er) buffer spring reduces felt forward impulse of the bolt as the next round is chambered.
     
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    rpoL98

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    I use AP receivers and BCGs exclusively and then may install a Rubber City bolt if offered with a custom barrel. I've never needed a dual ejector bolt. Bevel on the BCG is irrelevant if your buffer, spring, and buffer tube are correct/matched. Always test the buffer, tube length, spring, and BCG for compatibility before firing. With the spring removed, buffer should bottom out in the buffer tube with enough room to accommodate the BCG before it bottoms out in the receiver. Then install the spring and force the BCG into the buffer tube again - it should bottom out to the same distance that it did without the spring. If it doesn't go in as far then the spring is too long and is getting coil stacked. Fix. Mixing Armalite and DPMS buffer system parts can be a problem so I recommend this simple test just to make sure.

    As far as spring, buffer weight, and adjustable gas block - I like a heavy buffer (9-10 oz), lighter buffer spring rate, and reduced gas. Heavier buffer and reduced gas increase bolt lock up time and minimize felt recoil while the light(er) buffer spring reduces felt forward impulse of the bolt as the next round is chambered.
    agreed. but, that's a big "if" especially for somebody building their first ever AR-308. and don't forget to take into account buffer bumper compression if you're over-gassed right out of the chute. Another guy in another thread, must've either had a too-long buffer, or a too-short buffer tube, his buffer bumper got smashed, crumbled to bits.
     
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    Matthew488

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    Need help with choosing barrel length and diameter for an Aero Precision M5 build. This will be a long range build chambered in 7mm Sherman Short Tactical.
    What is the longest/ heaviest barrel you wound recommend? Shop I'm working with does up to 27 in finished length.
     

    Woodenyeti

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    AFAIK, Aero BCG is not Toolcraft. Aero 308 BCG has the chamfered rear of the fat part of the bolt carrier, Toolcraft has the squared-off sharp edges which impact the lower receiver upright and leave marks.

    Aero nitride 308 BCG has the small HP firing pin, bolt-face firing pin aperture, well suited for 6.5CM, and not a bad thing for 308 either.

    the Brownells nitride 308 BCG also has the rounded butt-end of the fat part of the 308 bolt carrier (and the HP firing pin set-up), at a much reduced cost, last time I checked it was about $140.

    AFAIK, there isn't a nitrided DPMS-pattern 308 BCG that has the chamfered fat end of the carrier, and dual ejectors, and HP firing pin/aperture.
    My Sharps Rifle Company BCG has the slanted bottom, and bolt has dual ejectors with smaller firing pin/hole.

    About to swap out that bolt for a JP HP bolt that was matched to my new Criterion barrel that should be here any minute. I don't have headspace gauges, and have been fighting to get my 308 ar10 to shoot decent groups with 168/175s since I built it. 16" Satern Liberty barrel hasn't been able do better than 1.5-2 moa over multiple 5 shot groups...so I didn't want to take a chance. No issues with their bolt otherwise, I burned about 6lbs of powder with it, mostly on unsuccessful load development.
     

    FALex

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    I recommend getting a BCG where the rear of the fat end of the carrier is beveled. Helps to prevent damage to the lower rcvr buffer-tube upright in inadvertent adverse situations where the BCG overtravels, due to whatever unintended reasons (spring, buffer too short/light, over-gassed, etc).

    utgjdfN.jpg


    SE5sylF.jpg
    You just do that work yourself with a dremel. Duh!!! :ROFLMAO:
    :ROFLMAO::ROFLMAO:
     

    rpoL98

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    You just do that work yourself with a dremel. Duh!!! :ROFLMAO:
    :ROFLMAO::ROFLMAO:
    @FALex the lower one is a Brownells 308 HP nitride. The Aero is similar, except it has the engraved logo.

    Sorry to burst your bubble, but my dremel skills aren't that good, and I certainly don't have a nitride furnace set up in my garage. But I'll take that as a compliment.
     
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    FALex

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    @FALex the lower one is a Brownells 308 HP nitride. The Aero is similar, except it has the engraved logo.

    Sorry to burst your bubble, but my dremel skills aren't that good, and I certainly don't have a nitride furnace set up in my garage. But I'll take that as a compliment.
    You know what, my friend? It’s probably for the best! LMAO!!
     

    stefan73

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    You'll probably be happy with either one of the choices you listed. I am currently running two of the Aero bolts and have no complaints at all on my .308 builds.
     

    FALex

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    @bigjake83 is running an "Enhanced" Lantac bolt in one of his rifles. After checking it out, I was extremely impressed. My brother is building a small frame, and when it came to BCG, I told him to grab the Lantac. We'll see how it performs, but I'm sure it's going to be just fine.

    Difference is, they are more expensive than the BCG's listed in this thread by a good amount.
     

    rpoL98

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    just one more data point, from Arm or Ally, I ordered one of their 308 nitride dual-ejector HP BCG's, and also one of their 6.5CM nitride dual-ejector HP BCG's. separate listings, $129.99. got both of them, they are the same. I guess it's just marketing that they have separate listings. Kinda figured they'd be the same, why wouldn't they be. The firing pin diameter is 0.065", same as the FP of my Aero HP BCG, in fact, the FP's are swappable between the Aero and the Arm or Ally Toolcraft HP bolts.
     
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    Argent

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    @bigjake83 is running an "Enhanced" Lantac bolt in one of his rifles. After checking it out, I was extremely impressed. My brother is building a small frame, and when it came to BCG, I told him to grab the Lantac. We'll see how it performs, but I'm sure it's going to be just fine.

    Difference is, they are more expensive than the BCG's listed in this thread by a good amount.
    Do you know what the firing pin aperture diameter is on the Lantac? I'm wondering if it's 'HP' or not.
     
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    FALex

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    Do you know what the firing pin aperture diameter is on the Lantac? I'm wondering if it's 'HP' or not.
    I am gonna let @bigjake83 answer you for certain, because I can't remember. From the minimal amount of reading I have done on the topic, I would venture to guess that it is not an HP bolt.
     

    bigjake83

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    I am gonna let @bigjake83 answer you for certain, because I can't remember. From the minimal amount of reading I have done on the topic, I would venture to guess that it is not an HP bolt.
    Do you know what the firing pin aperture diameter is on the Lantac? I'm wondering if it's 'HP' or not.

    It is in fact a HP Bolt, Firing pin diameter is .065

    They're a quality bolt you won't have any issues.
    IMG_20221221_205859119.jpg

    IMG_20221221_205942754.jpg
     

    B Man

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    Just to update this I got sidetracked building an AR15 precision rifle ahead of this. Just something about having one to shoot when me and my wife shoot (she has one) just seemed more appropriate. Anyhow, I did order an Aero M5 enhanced set a few weeks ago. After a long talk with the gentleman at Compass Lake I figured if it’s good enough for him it’ll work for me on this purpose. I’ll load up the rest of it with premium parts to run and shoot right and depend on some of you very knowledgeable folks to help. First thing is I’m sending it and the stock off to turn it another color. In the mean time I have to figure out what caliber I want this…. The simple and faithful side of me wants it in 308win, but I have an AR in 308 so thinking possibly something different on this one. Thank y’all
     

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    rpoL98

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    Just to update this I got sidetracked building an AR15 precision rifle ahead of this. Just something about having one to shoot when me and my wife shoot (she has one) just seemed more appropriate. Anyhow, I did order an Aero M5 enhanced set a few weeks ago. After a long talk with the gentleman at Compass Lake I figured if it’s good enough for him it’ll work for me on this purpose. I’ll load up the rest of it with premium parts to run and shoot right and depend on some of you very knowledgeable folks to help. First thing is I’m sending it and the stock off to turn it another color. In the mean time I have to figure out what caliber I want this…. The simple and faithful side of me wants it in 308win, but I have an AR in 308 so thinking possibly something different on this one. Thank y’all
    you want 6.5CM for your Aero AR-10.
     
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