the valve nut is not going to affect/adjust the velocity.
it just holds the valve in and compresses the o-rings.
the easiest way to bring it up to speed will be to shim the spring and hope it's right or drill & tap or buy a BBA that you can adjust with a allen key.
also your HPA reg needs to be set for high output. 800ish
these old untuned sheridan's work best on CO2
Last edited by Brassballs; 01-07-2013 at 09:04 PM.