I’ve been tinkering around with one of my 2250’s and turned it into a 9mm. Using a Max Flow Bulk valve, ports drilled out to 3/16, a heavier hammer spring, a RJ Machine Hi-Rise breech and a 14″ 9mm barrel, I’m getting about 400fps with a 77g Eun Jin. Any idea’s on how to get the fps up some more besides a longer barrel. I don’t think a lighter valve spring will help much since it already seems to have a good deal of excess Co2 coming out the end of the barrel.
I’d you’ve already got ‘snow” coming out the end of the barrel when you take a shot then I’d say you’re probably close to the limit on how much velocity you can get from that length barrel.
You could try enlarging holes and making a heavier hammer, but that will likely just waste a lot of CO2 and you wont make up much for it in speed…
Longer barrel, even though not what you want is probably the way to go here.
Might want to try and reduce the amount of co2 released per shot and see if the velocity drops considerably then you’ll be able to tell if your wasting co2 or not. Try a slightly lighter hammer or a slightly heavier spring. If it doesnt drop then you know your wasting co2 already and nothing much other than a longer barrel is going to help. If it drops then maybe there is still more you can do.