Hello again, I have received some good info on IMR powders and the 458 winnie. My next question is, what can be done to a long throat in a cast shooter, other than cutting the barrel back and rechambering? This particular rifle shoots jacketed very well, I just really want to get it shooting cast. I have not done a chamber cast yet. But, I have seated a few 600 grain Ballisti-cast bullets on the gc trying to touch the lead. never found it. I am presently looking for a 500-550 rfn gc bullet to work with. I used a 450 grain cast performance and it keyholed at 50 yards. Looking forward to any suggestions and help. Halfbreed