Okay, so me and my friend have decided we want to build an m4 with insane ROF, we decided we wanted a long barrel and we are also going to be buying 5000 round mags. Trouble is, we need help with the internals since we have no idea what we are doing with it. We just want insane ROF at around 350 fps. Things we need help with is the motor and gears and basically anything internal.