Just picked up a couple of FP-20's to play with, one with the chubby case (early style?) and one looks like the pic on Tower's web site. Figured the early style has steel liner/iron piston. When disassembled though, piston feels light, hmmm... Try to pick it up with a magnet, no go. Try to pick up cylinder with magnet, no go. OK, maybe sleeve is stainless, but if piston is iron shouldn't a magnet pick it up?
Thanks,
Ken