It has a H3 heavy buffer.
Has a standard +25% buffer spring.
The gas block is a Superlative Arms adjustable. When you adjust it to lower pressure, it vents the excess out a port in the front of the block. It's been adjusted to release to the limit it will go before, though next time I shoot this I'm going to take it all the way down and try it again, Because why not?
Same with various magazines.
I've talked to two good gunsmiths, one looked the rifle over thoroughly and said he didn't know, the other, after various talks, suggested it's cursed. Yes, I do know they're good. This one has them baffled.
I've done more reading the past couple of months on this type rifle, and various things people have tried on theirs...
I'm going to think about all this some more before I mess with it again, and go from there. And I do appreciate all the ideas. And I'll try to contact that one guy mentioned.
Added:
Magpul and steel magazines, bought different times and places.
Happens with factory and handloads.
And, copied from my comments,
I don't want to go to a heavier buffer, because I found out what that would cost.
Changing barrel because of port size, same.
The Superlative gas block has a total of 48 clicks of adjustment: from closed, open 18 gives you a fully open port, max pressure. With it open an additional 8 clicks it functions perfectly without the can. I've tried it with up to 46 clicks of bleed-off mode with the suppressor. I think I'm going to open it to max, and try it again now that it's all been fired and settled in a bit.
And I'll keep reading.