Happy Veterans day to all that served. Our country wouldn't be here if there were not people willing to raise that right hand and do what needs to be done.
Try the drum w/5 rounds. if it works increase the amount of ammo till failure. Might just be a strong spring that needs to be broken in. How much does your buffer weigh? What recoil spring are you running?.
Aero's 308 carbine buffer is only 3.8oz. 5.5oz range seems to work best.
Bet it is the recoil system.
This recoil system works.
https://www.armalite.com/SACItem.aspx?Item=AR10REKIT01&ReturnURL=/Armalite/Product-Category/AR10-Parts-Accessories&Category=4eeff98b-d9a6-40fd-be6b-ab2e44ec1080
Ran a few rounds through it left handed today. No problems hi brass 5's ejected @ 1:30-2:00
Here is where I picked up the 10 rounders.
https://www.classicfirearms.com/turkish-made-ar-12-mag-for-ar15-style-12ga-shotgun-fr99-mag-10rd/
I'm using 165gr nosler balastic tips in 308. Never had a deer take more than 3 steps. Turns lungs to jello. Sub 1/2 moa out of my bolt gun. Sub moa in my AR308. Not happy at all with the results I got out of the 125 gr creedmoor Winchester hunting ammo.
I bought one of these. Rural king had it on sale for $359.00
https://www.charlesdaly.com/product.php?id=689
It works well. Runs low brass and hi brass just fine. Was busting clay birds with it a few weekends ago.
Armalite uses a different thread pitch on the barrel nut along w/the slant receiver cut. Some use the DPMS thread for the barrel nut but have the slant receiver cut. I believe Diamond Back is that way. Palmetto does their own thing but uses the DPMS threading on the upper.