Do you have a bearing on both the spring guide AND the piston head?
It could be that the spring, when fully compressed and in combination with bearings at both ends, is too long and is causing the piston to bottom out before it returns fully to the rear - as the gears keep pushing, the piston can't go any farther back, so the last 2 teeth tear off.
Compare the length of your new spring to the stock spring in a fully compressed state (if you can): put each one in a vice, slowly and carefully crank it closed until fully compressed, and measure the length of each one. Since I do some gun doc work, I built a crappy tool to help with this:
If the M130 is longer than the stock spring, I'd almost guarantee this is the root of your piston problem.
An easy fix is to use a non-bearing piston head; you only need bearings at one end, anyway. The other is to either buy a shorter spring, or clip one or two coils off your existing spring (although this will cost you some FPS).