| I set up a pump cocker a while back for direct CO2. It already had the old style valve in it so I went with the recomendations of the MCB fraternity and put the stiffest valve spring from my kit into the valve area and ran a medium hammer spring. I originally set it up using HPA in the shop and it took the IVG to be screwed in quite a bit to get the velocity right. However when I switched to CO2 at the field and chronoed it was shooting OVER 400! ! ! ! I undid the IVG all the way and it came in at around 290. Based on that I'd say older valve, stiff spring and light or medium hammer spring as required to hit the velocity when the IVG is somewhere around the middle of it's adjustment range.
A low pressure valve will be a real bugger to set up for consistency since what you're wanting to do is shift the control away from the varying CO2 pressure acting on a big valve stem area over to a small stem area and control via the springs.
I'm assuming that this is for a pump conversion? You can't really expect a 3.5 or 9 oz to maintain pressure under rapid semi fire. It'll cool off and drop the pressure and your velocity will fall off somewhat. But for pump or strongly limited semi play it can be a nice light setup.
__________________
Model airplanes are cool too!
|