Great brace - SB Tactical SBT5 Pistol Stabilizing Brace for HK MP5/MP5K RS Clones

Bought this for my ZF5. Build quality is fantastic and locks into open position solid and stays folded when you want. Fit super snug and has zero rattle or movement when firing. The only issue I had with it was that the bolt carrier group would go back when cycling, it would almost always stick at the back. First time, I took it all apart, found nothing looking off, and reassembled it. Everything seemed fine...until the next shot. Same thing. I happened to strike the rear of the brace on the bench and it went back into battery. I did this a couple more times and it was, sure enough, just sticking to the rear. Took it home and tore into it. It appears the "buffer pad" in the brace is considerably thinner and "squishier" (for lack of a better term) than the one from the ZF5 pistol end cap. I took the buffer pads off and swapped them (this required a slightly longer bolt...easily found at the local hardware store), but worked perfectly. Returned to the range a few days later it ran with zero failures (through about 500 rounds). Really love it now and plan to get one for my ZF56 when it gets here.