APS Steel Teeth Polycarbonate Piston for Airsoft AEGs

"to start this piston is VERY VERY HARD!, I was surprised on how well built this particular piston is. I have it currently pulling a m130 spring in an A&K SR-25 (mind you I added a spacer inside of the cylinder so the gearbox will accept this piston usually the sr25 requires a 19 toothed piston NOT a 16 toothed) and currently the gun is shooting a healthy 462FPS with .2's and 410FPS with .28's.
I don't know how this piston would stand up to full auto firing (gun has been converted to SEMI only operation.) but iI am sure you wont have to worry about the piston failing from too much stress.
All in all another great product from matrix.