I have a CVA .45 - I never could get acceptable accuracy with 777 pellets - that could be part of your problem. With 777 pellets I could get a 4" group at 50 yards, but at 100 yards it was all over the place- nothing you could call a group.

When I switched to loose powder, my groups immediately improved. First season I had it I shot groups with both the 225 grain Powerbelt and 200 grain XTP. With the 225 grain Powerbelt I had the best results using 70 grains loose 777 FFG - groups were about 2.5" at 100 yards with a scope.

I would check your sights, make sure everything is staying tight. Then, I'd get some loose powder. If you want to stick with the Powerbelts, I'd start at 60 or 70 grains and work your way up until you find the "sweet spot". If they are legal where you hunt, I'd suggest buying a pack of the 200 grain XTP's and/or a pack of the 200 grain SST's/Shockwaves - these shoot the best out of my .45 - 1.5" 100 yard groups most days.