2250B Crosman new valve stem

[Shed tuner]

so reducing the valve stem diameter around the port will increase gas flow and raise fps, at the expense of gas consumption, yes.

but you are simply inputting more energy into a not particularly efficient system. The first mods I do to a 22xx are transfer port sealing (they normally leak) and an SSG, which noticably improves efficiency. A 19" barrel helps a lot too, but it's a bit long.

HTH - JB

[--ped--]

reducing the stem shank is one of the little tricks that add fpe but it works best when you do the full package of mods starting with flow into the valve followed by volume of the valve followed by reducing the valve spring tension (i tend to skip this bit as it can add to hammer bounce)
you then have gas flowing the stem and reducing the stem where it sits in the valve exhaust follwed by angling the port to 20*(works best if your making a valve from scratch)
you then get tp increase to 4.2mm with better seal(i like to mill the tp seat flat and use a gasket top and bottom like the p-rod pistol) followed by barrel port to 4.2mm(.22)

[Berber]

so reducing the valve stem diameter around the port will increase gas flow and raise fps, at the expense of gas consumption, yes.

but you are simply inputting more energy into a not particularly efficient system. The first mods I do to a 22xx are transfer port sealing (they normally leak) and an SSG, which noticably improves efficiency. A 19" barrel helps a lot too, but it's a bit long.

HTH - JB

And take coil off the hammer spring?

[Shed tuner]

And take coil off the hammer spring?

not if you fit the SSG