if you determine that its not the bolt catch or ammo then a free alternative to lowering the reciprocating mass weight is by punching out the rollpin on the buffer and removing the weights inside and putting it back together empty. i havent done it to an a2 rifle buffer but ive done it to a few of my carbine ultra lightweight builds and they run great and weigh 1 oz empty so its similar to a taccom buffer kit for example.

Yo, undergassing issue is definitely whay it sounds like.

Without spending any money, other than ammo, try taking out a steel weight from your rifle buffer. All you need to do is to punch the pin out on buffer and pull the rubber thing off lol. Very simple. Just try taking 1 steel weight out. I made my own rifle buffers varying from 4.3 oz. (Using aluminum rods from eBay) to 6.5 oz (Using tungsten weights from kak industry). I was simply experimenting with x39 uppers and 5.56 uppers.
 I don't remember the exact weight but I think 1 steel insert is like 1.?? Oz. So it'll prob be around 4.6-4.8 oz after 1 steel insert removed. You can take out 2 after and see if it's more reliable.

Regarding the bolt catch. That could be a problem but I highly doubt it. Check for excess play (muzzle to rear stock direction.) And binding. Highly doubt this but ehhh just looking is good enough and it'll take a whole 10 seconds of your life. Doubt it's ammo. Doubt it's your mags. Awm has always worked for me in the past but I guess there could be lemons out there. 0

Edit: if you have time, could you remove gas block and measure your gas port? Could always enlarge it by a fraction of a hair. Downside is that you would be removing the coating (if it's nitride or melonite) and could cause erosion faster. Not truly a big deal cause it'll prob be similar to a ss / 416 barrel. Also, hate to ask this but is the bcg lubed alot? I heard psa upper receivers are like dry as fuck. Idk if that makes sense. Saw it on YouTube before, many months ago when I was deciding on one of their fn uppers but decided to go with faxon mock dissy instead.

Good luck

I’ll take that into consideration, but I’ve already got a new carbine stock on the way since I know it worked when I first started this build (before I put on a A1 stock).
So unless I don’t like having a collapsible stock anymore, I’ll look into swapping out the A1/A2 buffer weights. Im familiar with the idea but never tried it before.

I’ve been using a brand new strike industries XBG (extended bolt catch) and it’s been working great especially for my small hands.