.45 Super - Development History

Development History

In 1988, a Gun World article detailed Grennell's efforts to update the .45 ACP for the 21st Century, a difficult endeavor due to the inherent design limitations of the veteran round. Introduced in the early 20th Century, the .45 ACP has a relatively large case capacity which was dictated by the relatively low pressure powders in use at the time of its development; as a result, it operates in the modest range of 19,900 – 22,000 Copper units of pressure (CUP). In contrast, current day cartridges using modern nitrocellulose powders generating higher pressure can produce a CUP in the 28,000 – 39,000 range. As it was originally designed for lower pressures, the .45 ACP case has relatively thin walls and weak case head and web specifications; it can’t reliably contain increased pressures. The layout of most M1911 pistols' chambers presents yet another challenge in that the case head is not fully supported in the cartridge feed ramp area; pushing the envelope in this critical area with too much pressure risks a catastrophic failure, resulting in a case bursting in the chamber. To rule out such a dangerous possibility, Grennell chose to use brass formed from the stronger and more modern .451 Detonics, shortened to the overall length of the .45 ACP design. Support for the case head was also addressed by adopting a new chamber and barrel design which reinforces the base area of the case. Other areas of the model 1911 pistol design were also strengthened, including the addition of a heavier recoil spring and a strengthened firing pin redesigned to prevent primer material from flowing into the firing pin channel under high chamber pressures.

Manufacturers such as Heckler & Koch (USP and HK45), and Springfield Armory, Inc. currently offer pistols rated to fire .45 Super ‘out of the box’. Although they will chamber, the firing of .45 Super rounds in non-rated standard .45 ACP automatics is not recommended, as doing so risks a case failure in the unsupported chamber and at the very least would batter the slide and almost certainly shorten the life of the pistol.

The .450 SMC is a variant of the .45 Super with a smaller primer pocket, which is touted as being stronger due to having more brass in the web area.