I knew I has some rubber gasket matiral out in the shed some place, well, I found it and cut out a buffer for the HK4 and it looks like it should work. The stuff is kind of like the red rubber erasers that we used to use in school. It has some give to it but not too much as to be useless as a buffer. I don't think it'll be as durable as a poly buffer but heck, for free it should work out pretty well and I've got enough to cut out a 100 or maybe more so if it only last for 1000 shots that'll be fine, I can make more for free. Anyway, I'll check back and let ya'll know how it works out. Talk to ya' later.