I can mail you
Do you have another AR-15 or have a friend real close that has one? You could swap that BCG out for a standard no frills job for a couple shots to see if it cures your ails. I'd be willing to bet that it's that bolt carrier group or a oversized gas block. Hopefully you get lucky...
A full gas system should cycle a H2 buffer. I think I have a standard buffer. If I can find it I will mail it to you on my dime Friday so you don't have to spend money on it. I don't ever use standard carbine buffers.
Shooting that Tula ammo will clog a adj. gas block up quick.
On gas blocks I like BCM. They are purposely undersized from them so you have to heat them to install them. A hear gun or sticking it in the oven will work also.
1. This may sound stupid but did you adjust the gas block to let all the gas through the system?
2. Was the upper new or pre-owned. If it was indeed 2nd hand the adj. gas block could be clogged up with carbon restricting the flow.
The fact that it has an adjustable gas block makes me think...
I was given that Pro mag because the tip hung on that from lip and would even start to feed. I knew I could get it to feed so I didn't turn it down. All my other mags are Magpul or rebuilt GI mags. If someone gives me a rifle that doesn't work I don't turn it down. I take it fix it and put it to...
I had a couple of 40 rounds Pro Mags that I had to do that on. Wouldn't feed woof a damn. I had to trim off quite a bit too. The bullet tip just got hung up on a little corner of the front lip. They work fine now but the didn't function from the manufacturer. You can see on both sides I had to...
I have had several builds just come about an inch to three quarters of an inch from fully chambering and it was the viton ring under the extractor. It was just too tight and didn't allow it to chamber around intermittently.
Also I would start with returning all of the standard carbine parts...
The idea was to keep overall length and weight down. I like that brake if I was going with a heavy range set up but since I built this 16 inch gun ( my other is 18 inches ) the smaller unit works in my favor. This gun shoots so soft it almost makes you question if it's a .308 or not. It actually...
I just bought a two port muzzle brake on eBay for 39 bucks. I drilled two holes in the top just to give each port a little help since there is only two ports. It's only 1.5 inches long and I though it might not do as good as a three port. Fortunately it shoots softer with this mini brake...
Go back to buffer and spring. If you don't like the noise put a thin, thin layer of grease towards the rear of the spring to dampen vibration, It does the same thing for .03 cents. Start with standard weight buffer.
Where is the cartridge when it hangs? Half in the front of mag and half out of...