Should i buy superior heavy if i already have slug A liner?

Are you shooting offhand or from a bench? 10 shots in 2” offhand is pretty good at 100 yards whatever you’re shooting. From a bench or other good rest I’d be less pleased. Shooting at a starling at 100 yards is probably going to be offhand and adding in things like wind you’ll be doing pretty well to hit 1 in 3. I’d be interested in seeing groups at 50 yards from a bench. I could be wrong but I have a feeling you are trying to solve the wrong problem.

Rick H.