AR10 BS Thread

OK so kinda a mini range report LOL. The first time I took the rifle out I shot a box of 308 147 grain fmj's through it as basically a function test and everything worked flawlessly.
Today I took it out to start zeroing the optic I only had 50 yards available to me today but I wanted to shoot and figured I could at least get it on paper so I had a head start when I get to go to the further range. I used a box of Winchester white box 7.62x51 fmj and accuracy wise it shot very well albeit only at 50 yards. It started a little low, about 2" and I just walked it up from there accurcy was better than expected with the ammo being used.
Issues: It started with some failures to hold the bolt open on the final shot, I had a couple of failures to feed, and a couple of partial feeds which jammed. @OnePuttBlunder IDK if these are like some of the issues you were having. Mostly it ran ok but too many issues to be happy with. From my understanding, 308 is a little higher pressure round than the 7.62 and I am wondering if it just needs the little bt of extra pressure to run correctly. I have heard these rifles can be finicky I guess my first step should be to try some 308 and see if the issue is resolved if so that is fine. I'd like to be able to run the cheaper ammo for fun but not if it doesn't work correctly.
Rifle is rifle length gas system and full A2 buffer assembly.
All 20 rouds


About the last 7 or so were all in the ragged hole at the bottom of the dot. I was only using the bipod and Lord knows I'm not God's gift to the rifle

 

Yes .308 is higher in pressure as in CUP. The tuning comes in with proper gas system set up. Starting with the barrel. Ending at the buffer and spring.

The jam or failure at the chamber is usually the magazine, short stroking is the gas system. It’s not unusual for home built rifles to have both problems.

edit:
Also you’d probably want to be about an inch low at 50 as your shot will be higher at 100. FYI.

 

Same issues @Casper66 mine has become a bit better with break in. Couple things to look at. Check your gas block alignment. I think mine was off by just a little causing enough of a restriction.

Pull your bcg/bolt apart especially if an aero one. If you haven't done so already pull the 2nd oring from the extractor and they double up the spring too so I'd try to remove that and test too(I'm doing that on my next range trip) then lube the hell out of the bolt and put it back in the carrier. The Aero bcg seemed to be incredibly stiff compared to a new AR15 bcg (BCM)
Definitely needs the new knocked out of it.

For me it didn't seem to be limited to .308 vs 7.62x52 I had the same issues with FGMM 175gr as I was with PMC 7.62 147 gr

 

Thanks for these responses. It has a BA 18" barrell with a rifle length gas system and I had them drill the block and barrell so the block is pinned and has the locking screws on the bottom so IDK how I can really align it any better unless they misdrilled the block or barrell. Yes it has the Aero BCG so I will take it back apart and try removing the Oring first but I didn't seem to have an ejection issue. As far as tuning, I admit I need to learn more about this but with a non adjustable gas block the only changes i can imagine making is to the buffer or buffer spring. If there is anything else I'm all ears. Magazines are Pmags so I am open to other suggestions I need more anyway
Thanks for the heads up on 1" low at 50. I'm planning on a 100 yard zero and play with distances from there

 

Palmetto build. Just added a Harris bi-pod and PRS Lite stock. Waiting for the weather to warm up so I can take her out and play.

 

Don't know if you're running rifle or carbine buffer but if running carbine like me this may be a good $20 spent. I just ordered one to try.
https://www.weaponoutfitters.com/sprinco-buffer-spring-ar10-extra-power-orange.html


Seems to be one of the main suggestions for common reliability issues

 

@OnePuttBlunder original statement of break in is a thing, at least with Aero AR10s for sure. It should really only be a few range trips, but they do settle, and start to work in after a box or two. If that’s not the case then, it’s something else.

I don’t reckon throwing springs at the problem right away is the direction to go though. However/but/Unless:

If running carbine length, it dun needs to be around 28 coils on the spring. If you don’t have that…it’s the wrong spring. If you’re running rifle length, it’s like 39 coils. If you find some random gay company like cmmg with 27 coils on carbine length or something, then use common sense, there’s bound to be manufacture variation to a degree. I’m not counting coils on every manufacture springs I own.

Checking to verify proper misalignment of the gas rings on the bolt, however unlikely is another check in the box. If the bolt is locking and unlocking, and slides into battery fairly easily, it shouldn’t be anything bolt function related.

That leaves correct length tubes, gas hole in barrel, and correct buffer size.

…Or again, could just need to settle.

 

Regular A2 rifle buffer not carbine

 

I checked gas ring alignment when I cleaned it and they were fine. The buffer assembly is Aero A2 buffer with the full length spring and buffer but I will pull and count coils.
Mechanically it’s all Aero except the Larue trigger and Ballistic Barrell( which essentially is still Aero) and the barrel has the rifle length gas tube.
I’m thinking like y’all I’ll just shoot it more and try some different ammo and see how it settles. As of now it only has 2 boxes run through it.
I can remove an o ring from the ejector as @OnePuttBlunder suggested but it never seemed there was an ejection issue more like a pressure and feed issue

 

Buffer spring is 39 coils I’m going to lube it.

 

Sprayed the buffer spring with Remoil and removed one of the O rings from the ejector now I just need time to go shoot again

 

@dfanonymous and @OnePuttBlunder i appreciate you guys giving me input. I like to learn and this is how I learn best. I can read tech manuals all day and not retain much but hands on and good discussions tends to stick

 

The aero Ar10 was/is definitely a learning curve for me. Was looking more at the parts spec this morning and they use a 3.8oz carbine buffer so I may swap that to a 5.4 as well. Also appears the buffer tube is 7 not the 7.75 inches it should be for AR10 which means for me the sprinco orange spring was a good buy. The BCG was just super stiff. I couldn't even get a clean extraction unloading it manually with the double oring. Then the bolt took excessive amount of force to rotate in the carrier.

If E forms holds true with the 90 day or less I should be getting my sandman within 30 days and hope to have it fully dialed in for reliability and tuned up to resume ammo selection/accuracy testing.


I'm a little over 200rds through it now and it has improved over time. Last trip ran 80rds of ammo inc 762 4 failures to feed properly. I think the revised buffer set up will resolve that now that the bolt has loosened up

 

Speaking of buffer systems as I was looking everything up last night and decided to order the sprinco orange I figured why not build out the SOLGW buffer set up too

 

My fully completed upper came in today so I thought it was a good time to get assembling the lower. I got the mag release button on....not too hard. Trigger and hammer group are now in....a little harder. I do not have a small enough Allen key to put the slide release in...darn it.
Where I decided it was time for me to stop was the detent for the front pivot pin. The detent fell out many times, but it is magnetic so I was able to find it with a strong magnet. I have decided to hang up the project for now as I do not want to throw this out my window!

 

The front pivot pin was the easier of the 2 for me, it’s different than the M4. Find a punch that’s close to the same size as the pivot pin, slide it through from the left side just shy of the hole for the stent and spring, depress the detent wit a tiny screwdriver or something then slide the punch over it to hold it in place, then carefully push the punch out with the pivot pin and the detent should pop into place.
Now I was 3 hours and 3 springs on the rear until I figured out, confirmed by Aero, you have to trim a few coils off the spring to shorten it enough to get the set screw in

 

Ok, lower is now complete, minus the buffer kit. I guess I will get to ordering my barrel and the rest of the stuff I need!

 

Did anything I suggested help at all? How fun I’m ready to start again but need to completely finish a couple things first. I’ll be curious to see what you end up with for parts for the rest of it

 

I'm really interested to see how the 8.6BLK from Q and Faxon pans out.


Q - 8.6 BLK - Velocity Testing - YouTube

 

Well, first thing this morning was going to Harbor Freight to pick up a punch set. One punch was small enough to go through the front hole and hold down the spring and the detent. I then found another one that went through the pivot holes and was able to hold everything down there. I then took the pivot rod, pressed it hard against the punch and was able to seat the pivot rod. I was very happy. Only had to chase the spring twice.

The rear pivot point and safety would have been WAY easier if Aero would have sent me an alan bolt of even a phillips bolt....BUT NNNOOOOOOOOOOOO, they sent me a bolt with a regular slotted head. That made it so much fun to hold everything together while I tried to look into the abyss of the handle and get a screwdriver on the bolt.....but it is done now.

The AR10 received set is much larger then I would have thought! I have a BCG in my cart with Aero. I think I am going to use all their parts as they probably engineer their parts to function together. I will probably look somewhere else for a barrel though as Aero always seems to be out ot 20" barrels!