I hope to get the final definitive answer to this most perplexing of questions. When shooting BPCR why use soft lead verses a harder alloy if the bullet is cast and sized 1-2 thousandths over grove diameter. It would seem that there would be no need for bumping up the diameter to fit and it would avoid nose slump. I could understand for hunting a softer bullet may deform better but at .457 or .512 does it need to. I know the knowledgeable people on this forum will have the answer.
PS I also have 500 pounds of #2 alloy.and only 50 pounds of 20-1.
Thank you
Nick