I have a CVA Optima Pro that i got for my birthday last year. i bought the CVA starter kit and it came with the copper series powerbelt bullets that are 295 gr. i used 777 powder and it grouped good at 50 yards. i switched to shockey's gold and it isn't grouping very well. i would like to shoot a lighter bullet. so any advice on what combination to shoot in my optima would be great.