Is there a formula or chart you guys go by. I recently got a .30 cal Maverick and am getting 60 shots off a fill which seems pretty good to me but I don't have anything to compare it to. What are some of you getting .30 cal 600mm barrel 480cc bottle 250-130 bar shooting JSB 50gr at 855 fps for 81 fpe which comes to 2 bar per shot