I pieced together an M5 from Shuyler Arms starting last spring and finally had a chance to shoot it this weekend with poor results and ending with a stuck live round that I had to take back home to get out.

Build sheet
-Aero complete 18" upper
-Aero complete lower
-Aero or AIM surplus bolt (have both but cant tell the difference, one has a darker finish aside from that identical, pretty sure the Aero is in the gun)
-Strike charging handle (tried a BCM but it hit the lower)

Ammo was older Silver Bear, want this to work in the AR since I cant run it in the FALs so thats what I used.

Recoil seemed more severe than a FAL but I havent shot a FAL in months so just a feeling, had a FTF after about 16 rounds, couldnt pull CH, a light pogo fixed it, looked like a light primer strike or a bad round. At about 45 rounds a jamb, couldnt close the bolt or pogo it open.

At home I had to pry the bolt open and found that the bolts lower rails had been hitting the lower at the recoil tube, leaving 2 nice peen/dents, worse on the right side. I checked and the bolt can barely touch, recoil must cause the buffer bumper to flatten slightly allowing the bolt to hit the lower.

I checked headspace quickly with the extractor and ejector in place and the bolt will close easily on a no go but not on a field. I should have checked it first but have been so used to AR15s i didnt even think of it until after.

I guess im looking for advise/solutions. I dont expect to be able to return any parts due to having purchased them some time ago. I want to be able to shoot this silver bear up since I have alot of it and found out to late it isnt good in FALs.

updated to add I tried my other bolt, also closes on the no go

"At home I had to pry the bolt open and found that the bolts lower rails had been hitting the lower at the recoil tube, leaving 2 nice peen/dents, worse on the right side. I checked and the bolt can barely touch, recoil must cause the buffer bumper to flatten slightly allowing the bolt to hit the lower."

What buffer tube, buffer, and spring combination are you using?

All Aero, the short carbine buffer setup

I have read that putting a light amount of grease on the rear part of the lugs will help with cycling during the break in process. I had my Aero bolt lock up  a round in the chamber and it was a struggle to get out. That was the last time I had my AR10 out. I'm trying the grease trick this weekend to see if it works.

I will try grease, i read on another forum not to be very concerned about closing on a nogo, not sure what to think about this, any opinions?
Also i put two quarters in the buffer tube to hopefully keep the carrier from hitting the lower

That's another .308 carbine with the correct short carbine buffer still slamming the threads of the lower at the RE tube boss.

We've seen it here many times now.

I wouldn't shoot steel case in these guns either.

This is the problem. I seriously don't understand why mfgs keep putting out incorrect parts for their rifles.

They use weak buffer springs, lightweight buffers, and full open gas. The buffer pad is probably flattening out, letting the bcg hit the lower.

Here is your fix, replace the buffer tube, buffer and buffer spring with either a Vltor A5 tube or Armalite AR10 carbine tube, with an Armalite AR10 operating spring and an H3 or heavier buffer.

I would also look into replacing the bcg with a JP or LMT bcg. Or hell, even a DPMS bcg would be a safer bet than any of the ToolCraft offerings right now.

Heavy buffer, buffer and spring and adjustable gas block fixed the issue for me.

ETA runs like a sewing machine now.

I ordered up a rifle buffer setup since i was thinking of a magpul stock at some point, also going to try an adjustable gas block.
I am hoping it will shoot steel cased because I have alot of it and the FALs cant

That could work. But i still highly recommend getting the Armalite operating spring. It's the same spring for both rifle length and carbine length receiver extensions if using the Vltor A5 or Armalite carbine tube.

If your BCG is hitting the threads on your receiver extension, you've got some incorrect parts in there. I verified my Aero parts on my M5 by running the carrier into the extension by hand until the buffer bottomed out. Plenty of clearance on mine. Verify your buffer and spring are correct.

Thanks for the info and thanks Aero, ill send an email out now

Waiting to hear back from Aero on the carbine buffer, in the meantime the rifle buffer setup from Midway came in so I set it up with that and a MI muzzle brake.

Bolt can no longer touch the lower, does not go far past the hold open, id say 1/8 max

Shot L2 ball this time to test, heres the breakdown

-1 round loaded, fired and locked back
-10 rounds loaded, fired, cycled 10 locked back, much less recoil than first outing
-Let a buddy shoot 5, 2 shots then click, didnt load. repeat, then shoots last and locks back
-He shoots 5 again, first 3 are single shots again, ejects but no new shell picked up. Last 2 cycle fine and bolt locks back
-I shoot 5, first 2 single shot then 3 run fine and lock back

This is repeated roughly for 10 more shots then I pack it up.

The parts are all DPMS per Midways site, I would have gone with an armalite spring but was trying to save on shipping. I will get one if it would really make a difference, im back to being at a bit of a loss on this thing

Any more thought or suggestions welcome

ETA the bolt has always been fairly difficult to pull back and doesnt slide into battery if ridden forward, it will close with a light tap of the FA though, It just doesnt seam to lock and unlock smoothly or easily, dont know if this is just because all parts and springs are bigger or what

Also i am hoping to not have to replace the BCG at this time.
I like the A2 stock on it and would like to get it going in that configuration if possible