CO2 Pistol

Hammer Spring
On Co2 and Gas Gun's most of them work by having a "hammer" striking a Valve releasing an amount of gas propelling the BB. To move the hammer most guns use a spring to force the hammer forwards. To increase the gas / Co2 usage per shot what you can do is make the hammer strike harder. This will increase the "open" time of the valve releasing more gas. There is 2 ways you can do this. One is to harden the spring. But the easy way is to just add spacers at the end of the spring.

To demo this I her have a Dan Wesson 8" (Used that one in the guide because it's easy to do the mod in this model but most slide models follow the same principle). Marked in orange is the valve that the hammer (hammer in blue) strikes. The hammer is connected to the spring (in read).

And adding the spacers (in yellow) will reduce the installed length of the spring, giving it more compression! This extra compression will push harder at the hammer, making it strike harder. And then the spring inside the valve will have to move more mass to close the valve again. So it will stay open longer releasing more gas.

Note that doing this mod to your gun will also increase the gas usage per shot, and reduce the amount of shots per gas / co2 refill! Another way to do this can also be to replace the valve to one with bigger output per strike. But increasing spring tension is free :-)