“A carbine length 9mm buffer is the same length as a std. or H/H2/H3 weight carbine buffer. The 9mm and H3 buffers are essentially the same weight and would be interchangeable - the only difference is that the 9mm buffer is a 2-piece style to combat bolt bounce whereas the H3 uses internal weights to combat bolt bounce. (see picture above - 9mm on left, H in the middle, std. on the right) I haven't personally compared an H3 with a 9mm buffer in the same gun with the same ammo, so you'd have to do that to see if you can tell any difference. “
