How to Upgrade an Airsoft Part 7

How to open a Version 2 gear box and upgrade your Marui gun to about 320 fps.

1. Gather the following:
   • Systema or other airsoft brand shims.
   • 6mm bushes.
   • A spring rated for 320 fps. A Systema m100, Prometheus m100, Guarder SP90 should be ok.
   • Airsoft grease (not car grease!). Lithium grease or G&P grease.
   • Philips head screw driver set
   • Torx screw driver set
2. Remove the V2 gearbox from your gun.
3. Ii there is a wire guide on the front of your gearbox directing the wires to the front, remove it with a screw driver.
4. Remove all the torque and hex screws from the shell.
5. Put a screw driver in the back of the gearbox through the spring guide and put pressure on it whilst you pull open the case.
6. If, when you open the shell the spring guide jumps out at you, remove the spring and spring guide as well as the piston.
7. Remove the gears and the anti-reversal latch. It doesn't matter if anything falls off the like bushes and shims, just not the teeth! (That would only happen if they were broken).
8. Remove the stock bushes and put your new ones in. Make sure they're a tight fit.
9. Shim the gears. Make sure the gears are correctly aligned and rotate well but don't move when you close the case. Put your gears and the anti-reversal latch back in place.
10. Remove your piston, spring and piston head.
11. Remove the piston head by unscrewing it with a rag and pliers.
12. Put your new spring in and re-attach the piston head.
13. Reinstall everything. Shut the gearbox . This will require a bit of effort but you'll get there eventualy. Put it in your gun and enjoy!