After the Civil War with the advent of metallic cartridges and centerfire rounds the Government was converting muzzle-loading muskets to cartridge guns. The first centerfire adopted was the .50-70 Government round. In 1867 the Navy was looking for a handgun for the sailors and crews of our ships. Remington developed the Rolling Block design in a rifle and a Navy Model handgun based on the .50-70 Government cartridge. That round was much too big and powerful for a hand held pistol. So they shortened the cartridge to a .50-50-500. The same lead bullet as used in the .50-70 Sharps, just shorter. They came up with the US Navy Model 1867. The muzzle blast was horrendous not to mention the recoil... but pretty damned effective at repelling boarders and topside enemy sailors.