This is a .45 caliber rifle. I really have little experience with a .45 caliber inline rifle. I do know that some other people reported having the same problems you are havinggetting their .45 calibers to "tune up." Others loaded something and they just started shooting them. I would think you are going to just have to search for the right projectile the rifle likes. That can sometimes be a long search. You might want to e-mail CVA and advise them of your problems and see what suggestions they offer...

I would have thought the powerbelts would have shot real well out of the rifle (shows what I know). My CVA .50 caliber Staghorn will shoot a lot of different projectiles very well with 90 grains of powder, but that does not help you...

You might want to get some Shockwaves and see if they will shoot well. They normally shoot well out of most any rifle they go into. Also the XTP's work well in all my .50 caliber inline rifles. I really wish I had more information to help you. CVA tech support might be a good bet. They are really helpful people there.