regulator setting?

Once you figure out the information that Mike VV suggested. You'll need to set the regulator pressure and hammer to get the pellet at it's most accurate speed.
Ex. 24 grain .25 cal @25 yards on a paper target - Speed 770 FPS 5 shot group 1"
Ex. 24 grain .25 cal @25 yards on a paper target - Speed 780 FPS 5 shot group 7/8"
Ex. 24 grain .25 cal @25 yards on a paper target - Speed 790 FPS 5 shot group 3/4"
Ex. 24 grain .25 cal @25 yards on a paper target - Speed 800 FPS 5 shot group 5/8
Ex. 24 grain .25 cal @25 yards on a paper target - Speed 810 FPS 5 shot group 1/2"
Ex. 24 grain .25 cal @25 yards on a paper target - Speed 820 FPS 5 shot group 3/8"
The above is just an example it could end up being faster or slower based your particular rifle.

Tuning is fun they say.
Good Luck

Smitty