I've made my first attempt at upgrading my G&G GR15 raider to have better trigger time. For the sake of this post, here are the relevant parts: SHS 13:1 gears | Magic Box 30K High Torque motor (Long-axis) | Modify 8mm ceramic ball bearing bushings | Modify shims | All other parts are stock G&G My biggest conundrum has been in the gears and shimming them properly. I shimmed them to the point where there was very little play (maybe 0.1-0.05mm if I could guess it), going from bevel to spur to sector. I shimmed each gear relative to the next. When I put the gears in all together, and screw the gearbox shut, they spin freely no matter what side I turn the gearbox. When I installed the motor and trigger, and plugged in a battery, the gears sounded like junk. I've looked up Youtube videos of how a good shim job should sound, and a guy who did a similar test setup got his to sound like a power drill. Mine sound like a blender. Here's the video for reference: And here's mine: I've tried shimming certain gears more loosely or tightly, and they only produce a variation of this blender sound. They don't make it go away. This sound occurs even when I install the anti-reversal latch and push the cutoff lever out of the way. Does anyone have any good suggestions? I've been at this for several days trying to figure out what is wrong with this gearbox, and I've done a ton of research on teching/troubleshooting, but I haven't encountered a problem like this. I want to figure out what's wrong with the setup and get everything running perfectly before I reassemble the whole gun.