The period of the late 1860s and early 1870s saw energetic competition between a number of revolver makers, the most prominent of which were Smith & Wesson, Colt and Remington. Smith & Wesson was busy developing a large-frame break-top. The first of these Model 3s were chambered for the .44 S&W American. It was not a true .44-caliber, using a bullet of .434-inch diameter in a rimmed centerfire case about .91-inch in length. .44 American cartridges used bullets of the so-called "heeled" type, where the bullet shank was smaller than the rest of the slug and fit into a bullet diameter-sized case. It is an older system that persists in such cartridges as the .22 Long Rifle. Bullets loaded with this method are about the same size as the cartridge case. There's something of a mechanical advantage to such a system in that the chambers are a little smaller in diameter and the cylinder can therefore be made a bit smaller. When a modern handloader goes about loading for the .44 American, he forms his cases from .41 Magnum brass.