You haven't built an AR platform until you work in the AR-10 world. Building an AR-15 is a piece of cake. Everything is standardized so the parts fit fairly well. Sometimes you have hiccups like civilian vs mil spec receiver extension tubes but that's minor and not real common. You can order parts online and be confident that assembly will be painless.

Enter the AR-10. Muther#&%#@*! I have been trying to build a light AR-10 for two weeks. At every turn this part won't fit that part without some luvin'. The bolt catch doesn't catch I've since learned why)(fix is in the mail). The pivot and take down holes do not exactly line up. The frickin firing pin take-down pin keeps falling out. Did you know the threads on an LR-308 upper are not the same as the threads on an Armalite upper? Okay. Figures. But I didn't think to check when ordering my handguard and barrel nut. So 50-50 chance.........I order the wrong one. I'm glad my shop is thickly insulated so Mrs df couldn't hear me roar.

Now tonight I go to assemble upper and lower with the charging handle and BCG and guess what? Charging handle won't go in. BCG won't go into battery. Turns out I bought an out of spec gas tube. 7/16ths of an inch too long. I though it looked wrong but perhaps if I ignore it the gun will assemble anyway. Nope. The charging handle just had a slight deformation which I remedied with a Dremel......the Bubba-smith's secret weapon.

Dude. Anyway, it's done and functioning manually. If I take it out and it fails, I'm probably going to weep in my hands. Just venting.

That is why I went the PSA route a few years ago. That and the pricing was just too good not too
Good luck DF.
Get some mags!

Yep. Mags. But they gotta be the right mags. Lol

Make sure you source the correct pattern when building a .308 AR
All my parts used in my rifle are DPMS pattern.
Plus when choosing an upper and railed hand guard, there are 2 different heights a high rail and a low rail. There is the low rail which is .151" tall, and the .210" tall rail.
Barrel extension is different also. If using DPMS or Armalite style rifle build, make sure to check all your parts for either DPMS or Armalite compatibility

The process of building an AR-10 is challenging / the struggle is real. I ended up researching every part prior to purchasing and it really helped out. There are a number of options out there right now for big bore AR rifle builds. I chose an Aero Precision M5 receiver set as cost was an issue. Palmetto State Armory, Mega Arms (good receivers), Knight's Armament (hard to find and are pricey if you can find a set) and LaRue (some of the best in my opinion) are among a few others. I am not sure if RRA currently makes a receiver sets or not. Perhaps someone here could answer that.

I would first decide what you plan to use it for. Are you cutting paper at 400+ yards or want to use it for shorter range purposes? Much of this decision will affect the length and weight of barrel as well as the gas system length you choose. Some carbine / mid length gas systems and buffers can try your patience especially if you plan to suppress. The bolt carrier groups you can find vary as well. There is variation in the weights, some dimensional differences (thousands mind you), and coatings. The most critical aspect is getting the bolt headspaced to the barrel you procure as there is no true mil-spec for these sets. Even if you get a matched bolt and barrel go ahead and pick up a set of go / no-go headspace gauges so you can sleep well at night. Their might even be someone here who would loan you theirs.

As for my build ..I picked up an Aero Precision upper and lower, 20" M110 patterned barrel (Criterion) and headspaced bolt from Fulton Armory, a Daniel Defense 7.62 Lite Rail (low DPMS profile), and an SLR gas block. The system is rifle length gas system with an adjustable gas block. The gas block has made tuning the rifle easy so that the bolt is not hammering the buffer and running a suppressor is easy. To date I have not had any issues using commercial ammo from 147g to 177g SMKs. YMMV but putting together a build sheet and researching everything will save you money and a lot of headaches.

My boys and I really enjoy assembling rifles so I wanted to make this process as seamless as possible but keep in mind it will take some tweaking after the build is complete. At the end of the day if I had it to do over again I would probably pick up a LaRue (I'm sure there are some haters here) because their customer service has always been great.

With all that said if you have any questions please feel free to contact me as my email is in my profile. I may not know the answer but I can find out or point you in the right direction.

Welp the parts came in to remedy the bolt catch issue. Guess what. No joy. Bolt still won't catch. Mother******. Upon closer inspection, I can see that the inner wall of the upper contacts the sloped portion of the catch and depresses it slightly. This prevents the catch from being fully deployed by the mag follower. This is an upper and lower set made by the same manufacturer so there should be no dissimilarity nor out of spec parts. So it looks like if I want my bolt to catch when the mag is empty, I'll need to Bubba-smith the upper. Lovely.

I had a similar issue with my Aero Precision bolt catch and ended up adding a Phase 5 extended bolt release and it solved the issue. The lip on the catch was slightly taller than the stock lower Aero parts kit.

What brand is the bolt carrier group?

quote:

Originally posted by 50 cal:
Make sure you source the correct pattern when building a .308 AR
All my parts used in my rifle are DPMS pattern.
Plus when choosing an upper and railed hand guard, there are 2 different heights a high rail and a low rail. There is the low rail which is .151" tall, and the .210" tall rail.
Barrel extension is different also. If using DPMS or Armalite style rifle build, make sure to check all your parts for either DPMS or Armalite compatibility

Yeah I forgot to mention the rail height differences. I did get that right but only by chance did I read about it before buying parts. But that is my point. Nothing is standardized so you have to be careful and willing to solve issues. When I built an AR-15, I can order nearly any part and it'll fit with few exceptions.

As far as the bolt carrier, it is a DPMS garden variety. I don't know why the firing pin retention device has to be designed so it can fall out. The AR-15 pin has a positive stop. Oh well, I'm just complaining like a kid. First world problems. lol

I thought about building an AR-10/AR-308 a few years back, and saw where people were having issues with reliability. I took that money and put it in bolt guns and have been very happy.

I'll build an AR-10 one day. Right after my primer stash recovers, and right after I get my hands on a 9mm AR that can take P226 mags.

I built an AR10 in 6.5 Creedmoor a couple years ago, I used a Sharps “Jack” 308 receiver set which came with the take-down pins and most of the rest of the parts are JP Enterprise. They headspaced the bolt to the barrel, it wasn’t any more difficult than an AR15. I used a Gisselle SSA-E flat bow trigger and Magpull PRS stock … and Fritz helped me pick out a Leupold scope.