I pushed the .30 cal JSB's to
50.15gr, 887max, 878av, 7.6sd (87.63fpe)
44.75gr, 927max, 916av, 9.3sd (85.41fpe)
The 25 cal 25.4gr maxed out at 1080fps (65.8fpe)
I haven't had a chance to play around with any .22cal but, if I can push the 25.4gr out at 1080 then I'd say it's a pretty good bet.
It's all a matter of settings and air consumption. I got those speeds out of the .30 cals by opening up the valve return all the way and maxing out the power wheel (I wouldn't recommend touching the regulator. It's set to a very nice level from the factory and in this case it was actually turned down.) It was NOT air friendly when I did this! I was wasting air like crazy but I just wanted to see how fast I could get them.
The 25cal is a more accurate representation of what to expect within "normal" settings. I can't find what my settings were for that but, I do have a 1065fps jotted down as Power MAX, Level 4 (.415"). This also sent the 34gr's out at 880.
When you open up that return valve adjustment you waste more air, but your speeds go up.
Be careful crossing over 1000fps. If you break the sound barrier your pellets will de-stabilize. You'll have to google what the sound barrier is at your elevation and environmental conditions.
Happy Shooting,
Tom
P.S. If you're going to start making adjustments to your Impact - Start a journal! Mark/write down all your factory settings.
Definitely get a good chrony setup.
Actually, just
go here. There's a lot of information there and
here's some tips for Impact owners.