Quit fussing over the .458s. 451-.452s work just as well. Better selection too.
I'm turning the XTP's inside out and causing them to shed cores with mild loads of 5744. I expect I will lose an animal with them someday if I keep running them at these velocities. Other than the barnse, I don't think that there's anything that's going to do much better in that diameter and I may just go that route, but it's always good to have options. Comparing muzzle velocities, it looks like the savage with the slower powders matches the 45-70 pretty well, and that's what the .458's I'm using are designed for.
