sounds like you have a lot of fouling in the barrell or you scope is no good,(" loose,recticals are messed up,or something else is wrong with it" )

I would clean the gun real good,take the scope off and shoot it and see if it hit where you aim.then put the scope back on and go from there.
(if you are shooting sabots,your gun may not like them,change to power-belts or maxie balls.0

There are a lot of things that could be wrong. Good luck in finding the right combonation of bullets and powder.