Its amazing I had similar experiences in the early 60's when I was collecting Sharps rifles. 45-2 7/8" or 45-3 1/4" cases had to be made, from Norma basic belted cases. Turning and threading the case base and using a 45/70 rim. What we will do to have fun with a big gun. You should see what a 550 grain paper patch bullet will do to a ground squirrel!!!
Bob