Version 2 full gearbox
 

I recently destroyed my m4's gearbox. Suffice to say it is beyond repair. What should I be looking for in a replacement? My Old set-up was for 400fps I'd like to be around that area again.

Modify S110 or S120 complete boxes seem to be pretty good but a bit pricey.

For the money I'd get a Lonex complete box, in most cases the internal parts are better than the Modify one and it's cheaper.

I bought the "M120" KingArms gearbox and it shot 410 fps in my M4 before i downgraded it. I am pleased with the quality of it.

Picked up the Modify 110 complete mechbox from airsoftparts.ca lubed her up and made sure everything was good to go, now that it's installed it runs like a beauty. Shooting right around the 400 mark.

Anybody have experience with the JG 7mm gearbox with included MOSFET? Seems like a good deal and it gets a lot of praise.

Solid box, MOSFET blows.
Might want to degrease, regrease and reshim, and AoE though.