I used parts from CarolinaShooterSupply, with Tromix modified Tapco hammer, Tapco forearm, folding stock... hogue grip.

about 97% of the time it's FTFeed and the other 3 is a stovepipe FTE. I've polished the top of the hammer and bottom of the bolt. It cycles by hand awesome, and occasionally cycles a whole mag fine. But especially when I quick fire it will lock up. Most of those times the bolt is about 3/4" from closing, and I have to eject the mag to get the bolt unstuck. I have a Tromix heavy hitter in it.