I wish I didnt put an M120 in mine, so far I have broken the motor contacts, the bolt, the tappet plate,
the spur gear (1 tooth missing) and the sector gear...(5 teeth missing)....
All pretty easy fixes I just haven't gotten around to buying the Items needed,
so lesson learned stick with the stock spring until you upgrade the gears, also
the blowack system is fragile, be careful
although, I love that gun to death, BTW when you get it, mind telling me what serial number you have....
I got #87
There are any number of reasons why these gears failed. No reason they failed because of the spring, most likely, and I mean no offense, lack of experience in a gearbox. In my learning days I broke a fair number of gears but from wear and tear. I can guarentee that if you do everything correct those gears will pull, and easily might I add, an M130 without any issues.