I would start by getting H20 case capacity and compare data to similar calibers like the 300 Wby. Quick Load might help once you have those figures. I'd look at H-1000, Retumbo and IMR 7977, and RE 26. With any of those it will be a very capable round. I might also consider a 9 twist depending on what you want to do with it.

I think that 150 and 165 grain bullets are a waste of the case capacity.

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