.45 Winchester Magnum
Date: Aug 13 2013
The .45 Winchester Magnum was announced in 1979 as a powerful option for silhouette competitors wanting to use an auto-loading pistol, but was also an excellent choice for hunting many big game species. Unfortunately, some of the pistols intended to house this cartridge have been limited in availability. It is most commonly encountered in the LAR Grizzly (a large version of the 1911 pattern) and the Thompson/Center Contender.
The cartridge is essentially a lengthened .45 ACP, but loaded to notably higher pressures of 40,000 cup. Original factory loads were advertised to push a 230-grain FMJ RN to 1,400 fps, but today the only factory load listed by Winchester moves a 260-grain JHP to 1,200 fps, which is clearly a better option for hunting big game.
To develop load data, Starline Brass was used exclusively, which is available factory direct at (800) 280-6660.
Standard .45 ACP dies can be used to handload the .45 Winchester Magnum, with an RCBS carbide set being used here. Since the cartridge is rimless and headspaces on the case mouth, a taper crimp is required. The case mouth was crimped to .470 inch, which can be measured using blade calipers. This offers enough bullet pull to keep them in place when feeding in auto-loading pistols, but also aids with powder ignition, which is especially important when using slow burning ball powders.
Powders that gave notable accuracy and top-velocities included Hodgdon H-110, Winchester 296, Accurate No. 9 and the old proven standby, Alliant 2400.