I don't specifically recall hearing of a .45-75, but it's not surprising to learn of it. They did a bunch of variants on the .45 rifle rounds. .45-70 Gov't is the major one that survives, but they made them with longer cases and more powder, the "-xx" specifying the grains of black powder the cartridge was designed to use (e.g, the .45-70 was .45 cal projectile over 70 grains of BP--and .30-30 is a .30 cal over 30gr. of BP).
My recollection is that .45-90 was relatively common, and .45-110 was the caliber of the Sharps "Quigley rifle" from Quigley Down Under. The biggest one I've shot was a Shiloh-Sharps in .45-120; the brass was 3" long, and, IIRC, each case cost $5 (in 1993 dollars).
My recollection is that .45-90 was relatively common, and .45-110 was the caliber of the Sharps "Quigley rifle" from Quigley Down Under. The biggest one I've shot was a Shiloh-Sharps in .45-120; the brass was 3" long, and, IIRC, each case cost $5 (in 1993 dollars).