Bigtimer - I too experienced the same problem with my CVA Optima Pro (.50 cal), but finally, after alot of trial and error, e-mails, and reading posts from other hunters experiencing the same problems, I found a cure. As far as bullets, I found that my rifle would consistently group the 295 gr. Powerbelts, w/ (2) 50 gr. T7 pellets. Lighter bullets were all over the paper.Note the word consistently. The groups were always in the 3"-3.25" range @ 100 yds.. Obviously I wasn't satisfied. I felt like there was something else other than changing bullets, that would help.
Guess what - I was right. After a tip that I read on the net, I felt like I found the extra"trick" for MY rifle. This turned out to be a mixture of 50% Windex / 50% rubbing alchohol, used for cleaning between each shot. The Windex would clean the barrel (not spotless, I wanted a small amount of fouling left over),while the alchohol would help dry it out.After each shot I would run a patch, soaked with this solution, down the barrel once (w/ breech plug removed), turn the patch over and run down once more ( one direction, both times). Before, I was using bore cleaner.Since I had the breech plug out, I would go ahead and clean off the face. Replace plug, reloadand shoot.
I attribute this one step,to tightening my groupsconsistently to.50"-.75" @ 100 yds.It's the only thing that I did different. As for the Powerbelt bullet's performance on deer - I don't have a single complaint. Out of 5 deer shot w/ this rifle and load, the longest recovery was 55 yds. Three were a pass through, and the other two were just under the hide on "exit" side. I am assuming that the two destroyed shoulder bones oneach of these two deer, slowed the bullet down enough to prevent a pass through. The key to a short recovery is shot placement, ratherthan bullet type. All 5 deer were in the 170 lbs.+ range. Distances were 85 - 165 yds.
Like stated on other posts- what works for me, may not work for you and your equipment, but I hope it helps. Good luck.