I have an optima magnum in-line rifle 1:24 twist. I tried for the first time yesterday shooting patched round balls out of it, the rifle is .500 cal and the balls were .490 I was using prelubed patches. I was all over the target at 50 yds. This rifle was giving me sub 2" groups last time I had it out with saboted .45 bullets. I tried both Shockeys powder and Hodgdon's Pyrodex RS, the Pyrodex was much cleaner but no more accurate, I was shooting 150 grains of powder. TIA for any insight.