Quote: One problem: The .500-.450 #1 had a thicker rim than both the .470 and .500. Such “thick rim” cases are not available afaik.
I have been using correct rimmed and formed Bertram brass which has lasted quite well so far but your method and headspacing off of the shoulder, as you mention, are good alternatives.
What does your case mouth blow out to? I find I have to partial neck size to get any grip on .458" bullets and I suspect that will shorten case life some.
-------------------- He who lives in the past is doomed to enjoy it.