Gentlemen: I backed down from the very high pressure/velocity loads with the Lee Precision 300 grain cast bullet and used a variety of pistol and shotgun powders to try to shrink the groups. Not much luck with any of them. Seem to run 4-6" in my Ruger 4 3/4 inch bbl off of sandbags at 25 yards. And way high as expected. Yeah, I know, you are going to suggest that someone else shoot this gun. I can lay them in the ten ring all day long with my S&W .44M or a custom .45 auto. Brass is prepared as it should be; SP primers, and sized to .452 with alox/beeswax. Tried moderate loads with Bullseye, HS5, 630, 296, and some old AL5. All shot to about the same POI with these large groups. All were 10 shot groups. No signs of high pressure; primers not flattened and the cases would fall out of the cylinder. Bullets are seated out and crimpted in place. The cylinder chambers all mike .452.
Your thoughts/suggestions, please.
Doctor Sam