I actually needed a buffer in my AK (homebrew reciever, made it from three pieces of 1/8" thick steel welded into a U and screwed on all the other parts), as the reciever was just a hair over the normal length (so the gap between the rear trunion and upper rails was slightly longer than normal), so the bolt carrier could be pulled back *just* far enough to pop off the upper rails and jam in the rear position (a slight tap on the dust cover or bolt carrier would send it flying forward again). I used two pieces of inner tube rubber for about 300 rounds worth, and switched to a Buffer Technologies model after I got around to ordering it and found time to install it.
It was a pain in the butt to try to figure out why my rifle kept jamming until I hand-cycled it with the cover off and saw how it was jamming up. :banghead:
Kharn