The .45 Colt was developed in 1872 for the Model 1873 Colt Single Action Army revolver (aka Peacemaker) and adopted by the U.S. Army in 1873. It was originally a black-powder cartridge, and due to its large caliber and heavy bullet, earned a reputation as a fight-stopper. It also proved valuable for big-game hunting as a standard sidearm on the frontier. Factory loads from the 1880s that contained 40-grains of black powder with 250/255-grain bullets reached roughly 1,000 fps and were the “magnum” cartridge and load of that era.

By around 1900, factory loads began to appear that contained smokeless powders, with the velocities being reduced to around 870 fps. Today pressures have been standardized at 14,000 psi, and velocities from Winchester and Remington are 860 fps.

When stronger guns began to appear, such as the Ruger Blackhawk and many others, handloaders began to load the cartridge to much greater pressures to increase performance. Several small ammunition factories are offering such loads, but they are not endorsed by SAAMI and are proprietary loads designed to be fired in specific firearms. Many of these loads generate up to 32,000 CUP. Following the use of more modern piezoelectric pressure testing equipment, some of these loads have been recorded at near 35,000 psi. Either of the above listed pressures will destroy black-powder-era guns, or guns that are of a weaker design.

In the past couple of decades, the .45 Colt has become very popular in lever-action rifles for cowboy action competitions and for hunting. Many of these rifles are relatively weak and should never be fired with loads that exceed SAAMI specifications for this cartridge. Stronger designs, such as the Winchester Model 84 and Marlin Model 1894 can easily handle greater pressures. The accompanying data exceeds industry pressure guidelines and was developed specifically for the Winchester and Marlin rifles and should never be used in antique reproductions or any weaker designs. Most of the loads are below 27,000 CUP, but again, do not use in any antique reproduction rifles, or revolvers that were designed for standard pressure loads.

Loads should be used exactly as listed. Do not reduce powder charges in loads containing spherical (or ball) powder. Apply a heavy roll crimp to assure reliable powder ignition and prevent bullets from deep seating when subjected to recoil and the inertia effect when placed in tubular magazines. Primers should be seated .003 to .005 inch below flush to assure reliable ignition.

To view the accompanying data, CLICK HERE.