Most gearboxes are Tokyo Marui compatible. I believe M60s and M249s use short length motors.

Check airsoftforum.com for more information. If you want to shoot a 300 spring, and you want a gun that does not break quickly, you need gears with a higher ratio than standard gears, and a battery capable ...

Thanks for the responses.

I am hoping to avoid purchasing a palmers regulator due to the high price and ebay seems to have a few alternatives:

http://www.ebay.com/itm/Spyder-Paintball-Gun-CO2-HPA-Air-Gas-Regulator-Bottomline-Drop-Forward-BLUE-New-/300648350246?pt=LH_DefaultDomain_0&hash ...

So here is my design for a 6mm qev semi automatic. Its only notable difference from normal qevs guns is its use feeding nozzle piston constructed from a blow gun nozzle.

Operation:

A: Check valve is open, gas flow in, this pressurizes the gas chamber and the feeding nozzle, which is pushed ...