I've had a AR Performance 16 inch MK68 build for quite a few years, and its been a great shooter. Upon moving to a free state, I added a suppressor to the mix.(AAC 762 SD) My once reliable rifle became a pain in the ass, way too much bolt speed and alot of failures to feed. Tried different buffers to know avail. I toyed with the thought of an adjustable gas block, but decided to try an adjustable carrier instead. Picked up a Bootleg unit and man what a difference. Before my brass was ejecting hard at about 1 o'clock, now about 3 to 4. 28.0 grns. of AA2200 is giving me 2515 FPS with a 115 SMK with good accuracy. Just thought I'd share Has anyone else played with an adjustable carrier on a 6.8?