+1 on G&P, they're tanks
G&P gears are notorious for breaking shafts, that's why I stress everyone to get the gears shimmed before even using it in one game.
Unshimmed, G&P gears last 1-3 games before breaking depending how you shoot.
Shimmed, the best I've seen is well over 120,000 rounds and they still weren't broken. The barrel was bent, the piston head was on the verge of catastrophic failure, and the piston was heavily worn.