I upgraded my amp mk2 to a brass piston and it's been good all I did was shoot fx a email and they sent me some under warranty for a friend's M3 I replaced. To be honest I don't remember how hard it came off I know I didn't use a cheater pipe on the ratchet just regular length 1/2 inch ratchet with the correct socket and put the gun in a soft jawed vise if it doesn't come loose easily smack the end of the ratchet handle with your palm to break it free
