I recently recieved a NOE .454-276 Keith mould in the RG2 hollow base configuration. I plan to fire these in my Mil Thunder Five chambered in .45 Colt/.410 3". The cylinder has no throats (.480" the whole way down, a .45 Colt cartridge will fit into both ends of tye charging holes) and the barrel has a groove diameter of .457" so that it can be converted to .45-70 with a simple cylinder swap (for sales in CA and MD). I've tried firing boolits sized .458" in it, and it worked to some extent, but I don't feel comfirtable using such large boolits in it.
So, here's my plan. I have cast some of these NOE hollow base boolits out of 30:1. I plan to size them .454" and load them over a stout charge of a fast powder in hopes that they will swell up and fill at least as much cylinder as one sized .458" and then continue on to fill the barrel. Am I way off base here? Any other cons8derations (heavy crimp, etc.)?