Building an AR10

[DeanSports]

I have built many AR15 in a few different chambers. I even finish my own lowers for most of them.

I am building my first AR10. I am probably just going to buy the Lower receiver. But was wondering if anyone has ever finished their own 80% lower for an AR10.

The 80% AR15 lowers are only about $40. so if I mess one up, no biggie. But the AR10's are about $90+ so it is definitely something I wouldn't want to mess up on.

Also, is there much different between building the 2 besides the LPK or is the AR platform pretty universal?

 

[AllenM]

it is basicly a larger version of the 15. But dpending on what buttstock you use it has to be able to have clearance for the longer charging handle. even though Ar15 and AR10 buttstoks will interchange.

 

[wsenefeld]

Make sure your handguard profile matches your upper receiver's profile. Some uppers/handguards have a high profile rail while others have a low profile rail.

Whatever gas system length you choose, buy an AR-15 gas tube if going with the DPMS pattern. When building my dad's AR-10 (DPMS pattern) I figured since it was midlength, an AR-10 midlength gas tube would work. I was wrong by 1/4" and the BCG would not sit flush inside the upper receiver because the tube was making contact with the gas key. I removed the 1/4" with a dremel and the BCG went home. Problem was, by removing the bulbous end on the gas tube, it didn't seal and there wasn't enough gas to cycle the system. Spent shell wouldnt even eject unless I put my YHM suppressor on. Swapped for the right gas tube and problem solved.

You may also want to get the Armalite AR-10 magazine catch. The one that came in my DPMS .308 lpk was for a standard AR-15 so only half the threads actually engage. For $12 I'm going to pick up the Armalite (when back in stock) which is the proper length.

 

[M67]

When you start buying parts choose a platform, LR308 (DPMS pattern) or AR-10 pattern (Armalite). There is a difference, and if you start buying a bunch of random parts you'll probably end up getting hosed because they won't go together.

For simplicity, the threads on the upper need to be DPMS pattern so you can use standard AR15 gas tubes and more DPMS style barrels seem to be available (Armalites use a different barrel extension and gas tube)

308s use the same receiver extension as the AR15 but be sure to get a 308 carbine buffer and 308 carbine spring. You can get a 7 position tube made for 308s so you cna use a 556 buffer but the spring has to be for a 7 position extension.

For fit and finish, buy a receiver set. They'll mate a lot better and look better. Even if a receiver is DPMS pattern or Armalite pattern, companies vary in fit from one brand to another (Like CMMG uppers don't look that great on DPMS lowers, and a POF lower requires a bhushing kit from Hogan to use on other DPMS uppers because POF uses AR15 diameter pins)

So it's easy to just buy a set from the same company. Mega, Seekins (hopefully soon), Black Rain, Aero, etc.

And like said above, make sure the rail height matches your receiver height. High tang, low tang, etc.

BCGs seem to weight a sh&t ton unless you get a JP low mass, so an Aero with forward assist notches might not be bad just because it probably does weigh a little less.

That being said, don't be alarmed about a lot of 308s not having forward assists. 308s are different animals than the AR15, a lot more power all round. There's a quote on one forum about a guy who worked for Fulton. Said that if a 308 didn't chamber, then that round has no business being in there. 308s are man spring so when it won't go in, eject it and go to the next round.

 

[DeanSports]

Awesome info guys. Thanks a apprecaite it.

I am going to post link to what I have purchased. below.

Barrel - 18" Barrel .308 ar-10 for sale at Ares Armor.
Upper with Forward Assist and Ejection Port - DPMS LR308 Billet AR-10 Upper Receiver - Ares Armor
Bolt Carrier Group - AR10 Phosphate Bolt Carrier Group, BCG ar-10 - Ares Armor

I also have the charging handle and muzzle break.

Looks like I am keeping it all DPMS. I have a CMMG 308 LPK. Should I get a DPMS LPK to put in it or will that matter?

Do you guys have suggestions on the rail to make sure the height is accurate?

 

[M67]

In my experience, CMMG LPKs are pretty nice for the money and I've never felt a bad trigger out of them.

The receiver is high profile, so just make sure you order a high profile rail. Troy, Fortis, CMMG offer high profile rails, just to name a couple

 

[DeanSports]

Thanks for your help guys.

I got my 18" stainless upper and bolt in a few days ago. Getting my lower from FFL tomorrow. Just have to get my hand guard in.

I am a little concerned about a stock assembly. Allen M you mentioned a longer charging handle could interfere with the stock. Is there anything that I can do to prevent that?

I am not too sure about which stock to get. I love collapsible stocks but I am thinking for this type of build it wont be needed. I am thinking the MOE Carbine Stock - STOCKS - MOE® Fixed Carbine Stock ? Mil-Spec Model

What do you guys think?

 

[M67]

You only run into the charging handle hitting the stock when you add a cheek piece or the comb is adjustable like the Magpul PRS (which they make a AR308 version) and the Luth AR MBA.

If you run a standard buttstock and don't add a cheek piece to it, you'll be okay

I had a fixed carbine on my 308 AR for a time, they're very lightweight and sturdy, plus very simple. If you shoot pretty close to nose to charging handle, it's a good stock. I halfway used mine as a target rifle and added the extended butt pad for a little extra length of pull

 

[DeanSports]

Hey guys just finished my AR10 build and I thank you all for your help.

Here are a few photos. Let me know what you think

Click Here For Photos

Stainless 18" Barrel
Magpul MOE Stock
Midwest 15" Rail
Ares Armor Billet Upper
PSA Lower Receiver
Cmmg LPK
Burris PEPR Scope Mount
Bushnell 6-18x50 Scope
Ares Armor BCG