I picked up a FWB 300 target rifle this weekend for a great price. Exterior has seen better days but will refinish OK. Shot into one hole for approximately thirty shots before the piston buffer disintegrated. I've found sources for replacement parts, but I'm cheap ( and the parts are not) and I'd like to take a crack at making a buffer. What would be the appropriate material? The stuff that is in there is a cream colored, soft, crumbly plastic. I was wondering if UHMW or Delrin would be a good candidate? Any suggestions?

Or Nylatron ...
Uprated car suspension bushes, spacers etc. are often useful for making bits.