The largest calibre for the Winchester Model 1876 "Centennial" rifle. Rifles of this calibre were sometimes called the �Cat Gun� due to the fact that many of them were used in Africa and India on lions and tigers. The short 300 grain express bullet had a reputation of delivering a tremendous blow up close on soft skinned game, but was also known to loose it�s velocity quickly at extended ranges due to it�s fat and stubby bullet shape. Rifles have a barrel twist rate of approximately 1 in 60�, so it is unlikely that bullets heavier than 350 grains will stabilise. Cases can be made by turning the rim down to .625� on .50 Sharps basic and shortening the case to 1.92�. Overall bullet length should be held close to 2.25� (+ or � a few) for reliable feeding. 

This text is based on information from “Cartridges of the World”, Hodgdon reloading manual, the cartridge designer and/or own resources.