If you have a recently tuned gun the accuracy may take a while to settle in. Polishing a leade, thorough cleaning of the barrel, and new velocities can affect the accuracy. Shoot the gun and give it a chance to settle in. If your power is bumped up you may find the pellet of choice has changed. Let the gun tell you which pellet it likes rather than trying to force the gun to group with a pellet it does not shoot well. Regulators take a while to fully stabilize too. Big bores often suffer with leading of the barrel at higher velocities if using too soft lead. Hard lead works very well if properly sized to the bore and reduces leading. Guns with LW barrels fitted almost never shoot their best right away, so shoot and clean, repeat, and be patient. Some guns really become "tack drivers" about the third owner! If your gun is shooting great and suddenly the groups explode clean your barrel. Borescope inspection of barrels that accuracy suddenly dropped off usually show some leading often in the choke area.