It's an echo 1 st6 which is a basic m4 pretty much. I downgraded the spring to a m90 spring but the piston is still stock. The third tooth is worn down because I'm correcting the aoe, here's some more pictures...
Should I just get the echo 1 piston again, or should I get a different one?
Last edited by ZanderFTW; June 1st, 2013 at 16:27..