Well the distance you started sounded good. Maybe the rifle was pushing the powerbelts too fast. My CVA shoots them with 90 grains of powder real well. While I used to shoot a lot of powerbelts, I kind of got away from them because of the price. Also the t-7 pellets with some good sabots like Shockwaves or 300 gr XTP's might shoot an excellent group for you. Just be sure to swab between shots with Windex and then dry patch it.