I had a NEF 44 mag rifle for years that shot very good groups with almost everything I stuffed in it. Sold it and picked up a new CVA single shot rifle in 44 mag. Group size is bad with everything. I am getting the best groups with 260 and 300 gr cast bullets sized 4.32" They are around 2.5" at 50 yards. EVERYTHING else, including several factory loads is grouping 3-6" at 50 yards. I have tried full power, very low power, mid power, and nothing works. The only difference I know is my NEF was a 1 in 38" twist, and the CVA is 1 in 20" twist. Tell me what to do.