Well I casted some lead in 405 gr weight and ordered my sizing die which came in at .457 which I knew was going to be too small. But I loaded a few anyway before honing my sizer to .458. The rounds at 457 shot terrible at 100 yrds grouping to 15 inches. Then I tried a few at .458 and the groups were noticebly smaller about 9-10 inches . Then at last I had honed my sizer to .459 and 4 inches was about average. I bet they would have been tighter if my shoulder wasnt all beat to hell. The 45-70 is a real beast with the stock rifle butt plate. I dont know if I should stop there or hone to .460 This was using 38 grains of IMR 4198 . Either way my next thing is to figure the drop at 150 and 200 yrds to have some fun with a gong.