The cartridge is an externally lengthened .45 ACP with a thicker web to withstand higher operating pressures.

The 45 Win Mag is nearly identical in dimensions and loading to the .45 NAACO developed by the North American Arms Corporation for their Brigadier pistol, developed to supply to the Canadian Army after World War II.

The cartridge did not gain much popularity due to the intermittent availability of the Wildey and LAR Grizzly pistols.

The cartridge was also chambered for the Freedom Arms Model 83 single-action revolver via an available optional cylinder.

[3] The .45 Winchester Magnum gained a following among IHMSA competitors as it provided the power and performance necessary to knock down targets at an extended range.