I have loaded several 45-70 loads that are jacketed .458 and have loaded 350 grain cast that are also .458. I just ordered some 405 grain cast that are polymer coated. These bullets are sized at .460. Is there anything I need to be concerned with using the oversized bullets? Will this oversize have any effect on pressures? I will be using IMR-3031 and possibly IMR-4198.
I have seen numerous shooters using the polymer coated bullets. I asked the load data and most were near the top end of the load data because they wanted 85-95% capacity. The loads shot fairly well. Most within MOA. Start at 80% and go up.