Bigted,
I used to own a C. Sharps business rifle in the 45-3 1/4" chambering. I purchased it in Richland, WA when the company was just getting off of its feet. Not knowing anything about reloading for BPCR back then the load I came up with was 100 grains of Goex FFg and a gas-checked Lyman 375 grain bullet alloyed at Lyman's #2 alloy. Allox lube. I don't remember how much neck tension was on the bullet. Surprisingly, it shot very well. I kept a target for years but lost it when I last moved. It was a ragged 2 1/2" group shot at 100 yards. I sold the rifle years later to a fella who lived in Alaska, and he said it was the very best moose gun he'd ever owned.
This is a photo of my wife shooting the rifle at over 800 yards distance...
Robert