.308 Lowers

So on memorial day. I found a sale on Armalite .308 lowers that I couldn’t pass up since at some point I would like to build a .308 and 6.5 Creedmoor ARs. I’m not in a hurry but I started looking for an upper and I cannot find an upper that will work. I can find upper and lower sets but no uppers. As I am also finding out (please keep in mind I haven’t built an AR-10 before but have done several AR-15s) that .308 lowers and uppers aren’t universal quite like AR-15 lowers. I am not sure why exactly that is so that is part of my question. Also, do you guys have any leads on uppers that would work with the Armalite lower? Lastly, do you think I should just sell these two lowers and buy different ones?

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@Ambassadors

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Try Diamondback for an upper. They are cut for the Armalite lowers. They use dpms pattern barrel nuts but the upper fits the Armalite lower.

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The AR15 platform has a military specification that all manufacturers must adhere to so parts are pretty well interchangeable. The 308AR platform was never a military firearm so the manufacturers will make changes to the design as they see fit. Sometimes it is to make what they see as improvements. Other times, I think it is to make a proprietary part to make money.
There are 3 main categories: AR10 which is Armalite, 308AR which is DPMS pattern, and LAR8 which is Rock River and early Bushmaster. There are some parts interchangeable but many are not.

Have you checked Armalite’s website? You can also try calling them to see if they have something not listed on their site. @98Z may be able to point you in other directions.

If you got a good deal on them, I would keep them to build. DPMS pattern 308ARs have more compatible parts available. I would steer clear of Palmetto State’s PA10. They are cheap but frequently need upgrades to make them function correctly. There are many such stories over on forum.308AR.com.

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Which Armalite, A or B pattern?
I am not aware of anyone that makes uppers to fit either Armalite brand lower. Several have the same angle cut but none that I am aware of will actually mate up and function. I have two different matrix sets and an Armalite B pattern, none will interchange. I think the DB is actually a Matrix Aerospace forging, no way to confirm this though.
Call Armalite.

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Have you actually ran a rifle in this configuration?

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Honestly I don’t know if it is an A or B. Is there anyway I can tell? I know the ad said that they did accept Pmags if that helps too.

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It is an A if it takes Pmags.
I have read many times that Noveske mates up, if it does odds are you could buy a whole Armalite rifle for the cost of a Noveske upper, if you could even get one.
https://www.noveske.com/products/12-5-gen-iii-leonidas-switchblock-n6-rifle

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No going by a thread over on 308ar.com

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Link that thread, curios, betting it is talking strictly about the angle cut, don’t recall anyone ever stating they have this combo functioning.

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I think I might try and sell these and buy an Aero Set. So to further my question is there anything else like this I need to be aware of? like once I have a matching upper and lower will any barrel work or are these the same kind of deal? What about LPK? are these the same?

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Barrel and bolt need to be the same pattern, Aero would be a DPMS pattern, better than 95% of the barrels and BCG’s you find are DPMS pattern now. LPK is dependent on brand, I would recommend getting the Aero LPK, good quality and sure to fit, many makers use the standard DPMS LPK but some have differences, mostly on the pivot and takedown pins.

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Sale it if you can and go DPMS pattern…

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Yeah thats going to be the plan. I put them up on armslist and I think I already have one sold. Guy wants to meet on saturday. I got a good deal on them so Im only asking 120 basically so I can recover my costs.

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I must have bad luck at finding barrels. There were a couple times I thought I had found what I was looking for (stainless, 16" with carbine length gas port, heavy contour), but e-mails to the vendors resulted in replies that they were using AR-10 barrel extensions, not DPMS extensions. I eventually gave up and ordered a DPMS 24" bull barrel and set it aside until I have time to reprofile it and cut it to 10.5" for a pistol build.

Tactical Machining seems to have switched from DPMS pattern to AR10 pattern, for their Gen2 80% .308 lowers. I had thought that things were slowly shifting toward the DPMS pattern being the most common for .308 builds, but then I see some sources apparently shifting the other way.

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Most makers/sellers only carry DPMS. Faxon, Ballistic Advantage, X-Caliber, Aero, Criterion, Fulton Armory, and on and on the list can go. Many will use the term AR-10 but are actually DPMS pattern when you read the details.
I would be interested to find out who is using true AR-10 extensions on their barrels as I have had the opposite result with nearly all being DPMS except Armalite themselves, Noveske, and a few boutique sellers/makers.

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Since I was shopping for something to modify for use in a pistol build, I was trying to stay near the low end of the price range.

First hurdle was finding 16" barrels with a carbine length gas system, as most seem to be shifting to mid-length gas system on 16" barrels. Wanting stainless ruled out a few more.

If my memory isn’t off, Bear Creek Arsenal was one of the places where I found what I was looking for, except that their description seemed to imply that they used AR-10 extensions, and an e-mail asking for clarification got a reply that the barrel came with an AR-10 extension, not DPMS. Looking at their site, now, it looks like that barrel was discontinued, and replaced with a mid-length 16".

I don’t remember who the other supplier was, but they also replied that the barrel I was inquiring about used an AR-10 extension, not DPMS.

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You got bad info on Bear Creek, they only sell DPMS pattern, it says AR-10 but they just use it as a generic term.

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They may have had somebody new handling e-mail questions, that day. I dunno.

For paying over twice the price, I get to cut and reprofile the barrel, then drill a new gas port, but I’ll have at least a foot of leftover barrel to use for some future project (or to stumble over in the shop, years from now, then wonder where it came from, before pondering if there’s something I can use it for).

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Bear Creek is DPMS-patterned on the extensions. I spoke directly to the owner at SHOT this year about that. The other stuff that jtallen stated is right on the money…

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