I'm looking to shoot my 500JRH with a heavy boolit (over 400 grains) in the 950-1050 fps range.

The obvious go-to would be some sort of a 440gr GC like the Accurate 440BG
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However, I do not know why 440gr is considered ideal. Why not 450gr or 465gr?
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Even somehthing like Accurate's 500gr 50-500M adds the extra weight in the nose, sitting no deeper in the case than the 440gr
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Would love to hear some personal experience/opinion from anyone who has experimented with shooting heavier boolits out of a 500JRH/500WE in this velocity range.