I've got an Armalite M15A2 gov. profile barrel, w/ rock river 2 stage trigger installed, as well as a G27 Samco grip installed. This does have a mid-length gas system
I've put about 700 rounds through the barrel without a single FTF or FTE.
If you're interested I could throw in a mount for the carry handle and a simmons red dot. email me if this interests you. thanks for your time.