Originally Posted by Penarol10
So the problem with the 99+ valves is that they sweetspot ~400 psi. What will happen if you hook up unregged 12 grams to it is that as the pressure gets lower on the cartridge you will get massive shoot up. As in a gun that is shooting in the 280's on the first shot will be in the 360's towards the end of the cartridge. Either get a valve designed for high pressure(like the palmers) or use a regulator.
Thats the function of the springs, not the valve. You can spring the 99 valve to sweet spot higher. For 12 gram use, the older small passage valves seem to work best without a regulator. And as someone else said, the original Sheridan style springs work real well with unregged 12 grams. You need a hard valve spring to reduce the shoot up, as the spring provides consistent pressure on the valve seat regardless of what the pressure is at from the 12 gram.