AR-10 Lower Question(s)

FPrice

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I've never paid much attention to AR-10 rifles in the past but that seems to be changing now. And that has me asking a few questions to build up my knowledge base.

What is the difference between an AR-15 and an AR-10 lower? I am assuming that the -10 lower is beefier to handle the larger cartridge. But from some of the parts kits I have bought it seems that the lower parts are common to both.

Does the AR-10 require a larger stock? I am partial to ACE Skeleton stocks on my AR-15 carbines but wonder if an AR-10 would do better with a larger, more substantial stock.

Just a few questions to start the discussion.
 

Rob Boudrie

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Same stocks, larger mag well and general size.

And unlike ARs, one cannot assume AR lowers to be compatible across brands (so says JP of JP).
 

FPrice

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Thanks for the clarification.

One of the articles I skimmed through mentioned two different styles of magazines, SR-25 and (what I assumed was) AR/Armalite.
 

JRT

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Thanks for the clarification.

One of the articles I skimmed through mentioned two different styles of magazines, SR-25 and (what I assumed was) AR/Armalite.
Correct, the SR-25 pattern (Stoner Rifle) is not compatible with the Armalite AR10. If I were building one I would go with SR-25. Usually trigger parts, safety selectors and buffers are common parts but not exclusively.
 

JRT

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I should add if you live in a ban state the AR10 pattern may be better. You can easily alter M14 mags which are plentiful and probably affordable if you are mag limited.
 

amm5061

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Correct, the SR-25 pattern (Stoner Rifle) is not compatible with the Armalite AR10. If I were building one I would go with SR-25. Usually trigger parts, safety selectors and buffers are common parts but not exclusively.
Yup, and if you go with the DPMS pattern even the uppers are finicky to match with the whole high vs low thing.

Not standardized at all.
 

FPrice

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Yup, and if you go with the DPMS pattern even the uppers are finicky to match with the whole high vs low thing.

Not standardized at all.
Dang. Sounds like if I want to minimize potential problems I would be best served by getting an Armalite lower to go with the upper which I made a impulse buy of.
 

amm5061

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Dang. Sounds like if I want to minimize potential problems I would be best served by getting an Armalite lower to go with the upper which I made a impulse buy of.
Get an upper that matches the pattern of the lower. Does the part of the receiver that accepts the buffer tube curve up, or come up at an angle?
 

Rob Boudrie

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Yup, and if you go with the DPMS pattern even the uppers are finicky to match with the whole high vs low thing.

Not standardized at all.
Safest to buy a matched upper/lower pair from a single manufacturer, or stick with an HK-91 or better yet PSG-1, or perhaps an FAL.
 
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jpm

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I find there is much more stuff available (uppers, accessories, parts, mags) for DPMS pattern than the others. I've had no trouble using different uppers (308 * 6.5CM) from 2 different makers on 2 different DPMS pattern lowers by two different manufacturers. Swapped around the other parts too without issue.
 

wmass

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Here’s a pic of my two 10 lowers. The top is an Armalite AR-10b (m14 pattern mags) and the lower is from our Matrix group buy (pmag). You can see the obvious differences at the magwell. All the parts are interchangeable between the two lowers except for the bolt catch. The uppers are NOT interchangeable.
 

Attachments

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Here’s a pic of my two 10 lowers. The top is an Armalite AR-10b (m14 pattern mags) and the lower is from our Matrix group buy (pmag). You can see the obvious differences at the magwell. All the parts are interchangeable between the two lowers except for the bolt catch. The uppers are NOT interchangeable.
Going solely by the angled cut at the rear, both of those receivers are Armalite pattern. The fact that your Matrix receiver takes pmags (SR / DPMS style mags) means it is a "Series A Armalite "
This is a great example of the non-compatability of "AR10s", better generically referred to as "308 AR pattern rifle"

Like Rob said, an upper and lower from the same manufacturer is your best best. Assembling parts from there can still be tricky. Their are different gas tube lengths across manufacturers, different barrel nut thread sizes, even some different take down pin sizes. To top it all off, their are now "small frame AR10s" available form several manufacturers that have their own unique dimensions

more info here
Decoding The AR-10 Lower Receiver | Gun Digest
Small Frame AR10 vs. Full Size AR10: What's the difference? - F4 Defense
 
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My AR-10 is HEAVY. Probably my own fault, billet upper/lower, heavy barrel, long handguard, and big optics...
 

citoriguy

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I was wading in this pond too, and it’s dizzying on the different types and compatibilities that are out there. I bit the proverbial bullet and went with AP. So far, so good.

Also keep in mind that if you want to put an optic on it, you will need something that can handle the recoil. I don’t know how much of that is BS, but I did buy a 7.62x51 specific scope.
 

CrackPot

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its gets more fun when you start looking at uppers. DPMS high. DPMS low. thread pitch of the barrel nut. You want to get a matching upper, lower AND handguard if you want to rule out the worst of the possible incompatibilities.
 

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I was wading in this pond too, and it’s dizzying on the different types and compatibilities that are out there. I bit the proverbial bullet and went with AP. So far, so good.

Also keep in mind that if you want to put an optic on it, you will need something that can handle the recoil. I don’t know how much of that is BS, but I did buy a 7.62x51 specific scope.
AP? It's too early in the morning and I'm drawing a blank.
 

JRT

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Going solely by the angled cut at the rear, both of those receivers are Armalite pattern. The fact that your Matrix receiver takes pmags (SR / DPMS style mags) means it is a "Series A Armalite "
This is a great example of the non-compatability of "AR10s", better generically referred to as "308 AR pattern rifle"

Like Rob said, an upper and lower from the same manufacturer is your best best. Assembling parts from there can still be tricky. Their are different gas tube lengths across manufacturers, different barrel nut thread sizes, even some different take down pin sizes. To top it all off, their are now "small frame AR10s" available form several manufacturers that have their own unique dimensions

more info here
Decoding The AR-10 Lower Receiver | Gun Digest
Small Frame AR10 vs. Full Size AR10: What's the difference? - F4 Defense
I wasn’t going to bring up the small frame AR-10 because it adds a third variable. I really like them, they shoot exceptionally smooth and the ergos are familiar if your shoot AR15 a lot. This is mine, you can see the grip is moved back to make room for the mag well. These are essentially adapted AR15 lowers. Mine is from POF.

0A435CB9-8BFB-446F-994A-363F3894859F.jpeg
 

Rob Boudrie

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One thing I like about the JP .308 AR is that the handguard diameter is a typical AR15 diameter, and identical to that on their .225/5.56 ARs.
 

Mountain

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No need to overthink / over-complicate. Matching Aero lower & upper, AR-308 mag release, BCG, barrel, appropriate buffer. Most everything else same as AR15- trigger, stock, grip, etc.
 

citoriguy

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Likely aero precision.
Yes. Aero upper and lower, Aero LPK, Geissele trigger, Fail Zero BCG, and some other stuff. Waiting for Black Friday or Cyber Monday to see if I can pick up an Atlas bipod on sale.

Again, between the DPMS, Armalite, LR308, and other variants, I’ve read several threads on multiple forums about people picking up incompatible parts and dealing with the issues therein. It seemed like a huge money suck, and I wanted something I could “build” and be reasonably certain a pull of the trigger yielded a bang.
 

FPrice

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For your build, $99.00 for an AP lower.

Looks good, except for:

"FFL
Products require a Federal Firearms License to be on file. If we don't have a FFL for you, your order will be put on hold until it is received. Please email [email protected], fax 641-623-8143 or mail a clear signed copy to: Attn: FFL Dept, 200 S. Front Street, Montezuma, IA 50171. You must be 18 years of age or older except in states that require an individual to be 21 to purchase Rifles and Shotguns also 21 years of age or older to purchase handguns, Lower Receivers, Suppressors. "
 
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