UC, GREAT SHOOTING! I use the Lee 459-405-HB but I shoot mine paper patched. My bore is .458 and I size to .451, then paper patch them and size them again to .451 They fit snug and shoot GOOD!
SS, here is a thought. How about A 43 mauser mould. It throws to .446 and then you paper patch to about .452 if these don't go down good enough for you then size to .451 and you will have a jacketed bullet that looks like this


And shoots like this!


This was with a TC Renegade, Green Mountain 1-18 twist .458 Ron