||This article includes a list of references, but its sources remain unclear because it has insufficient inline citations. (September 2014)|
|Place of origin||United States|
|Parent case||.451 Detonics|
|Bullet diameter||.451 in (11.5 mm)|
|Neck diameter||.473 in (12.0 mm)|
|Base diameter||.476 in (12.1 mm)|
|Rim diameter||.480 in (12.2 mm)|
|Rim thickness||.049 in (1.2 mm)|
|Case length||.898 in (22.8 mm)|
|Overall length||1.275 in (32.4 mm)|
|Primer type||Large pistol|
|Maximum pressure||28,000 psi (193 MPa)|
|Test barrel length: 5 inches
The .45 Super is a smokeless powder center fire metallic firearm cartridge developed in 1988 by Dean Grennell, a well-known writer in the firearms field as well as managing editor of Gun World magazine. Born of a desire to update and improve the 1906 era .45 ACP, the .45 Super cartridge is dimensionally identical with the older .45 round, but offers an average 300 foot per second (ft/s) improvement in muzzle velocity. The cartridge was co-developed by Tom Fergerson and Ace Hindman.
In 1975, Dean met at the Manhattan Beach Police Department indoor range with police officers R.L. Rowsell (BHPD) and C.D. Rowsell (CCPD). Dean brought his chronograph, his T/C Contender single shot, chambered for .45 ACP with 4X scope and a camera. The officers were working on a .45 ACP bullet and powder loading which would be more effective than the standard cartridges using hardball, semi wad cutter and hollow point (expanding) bullets. The state of the art hollow points were incapable of reliable performance across various conditions due to under 900 fps velocity and various design constraints . The meeting with Dean was to test the best bullet type (255 grain .453 diameter Long Colt semi wad cutter), most accurate powder/loading (Winchester 231, 680, Alliant Bullseye and 2400) and bullet velocities. Prior component testing had shown these components to be the best performing out of the multiple combinations tried. The testing this day found the Winchester 680 ball was the most accurate powder. This was the case regardless of the various grain loadings of 680. Winchester 680 was also the slowest burning powder of the four tested. Chronograph tests showed bullet velocity for all loadings in the range of 1150-1250 fps. The energy of the bullets according to Dean's calculations were "at .44 magnum energies". Problems noted with the larger powder loads are detailed below in Dean's efforts in 1988. The two most notable in 1975 were the large pistol primers would completely flatten and have metal flow. The unsupported portion of the case (barrel feed ramp area) would have swelling, especially with the heaviest loads. This would only happen in the unsupported area . Both primer and case issues are indications of over pressure of the case. When the same loading was fired in the T/C Contender (a single shot pistol) the entire case was supported and no swelling was apparent. The primer issue was also less notable in the Contender. The T/C Contender was a new weapon for Dean at the time of this testing. He had drilled and tapped some "blind holes" in the barrel to mount a 4X scope. With the addition of a liberal application of an epoxy, Dean felt the scope would remain in place. Unfortunately, the small screws sheared off and the epoxy failed as well after approximately 20-25 rounds fired, putting a small "scope smile" in the top of the shooters forehead. Some of the lessons learned included these types of loads required heavy duty barrels and 22 lb. recoil springs. (BarSto stainless and Colt Gold Cup stock barrels were used.) The weapon slide cycling time was visually and felt as being much quicker, yet the muzzle rise did not look or feel any greater. There was a definite increase in side torque or "twist" of the weapon in the shooters hand, which may have been from the heavy (and slightly oversized) bullet rotating in the barrel. Summary: Both Officers settled on the following loading as a duty load - 255 grain .453 diameter Long Colt bullet, 6.5 grains of Winchester 680 ball powder (no longer manufactured) with Winchester large pistol primers. The cases used were one time fired Federal nickel plated cases which were originally loaded with jacketed "hardball" bullets. As for Dean Grennell and his interest in bringing the .45 into the 21st Century, it was long before 1988. 
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 cannot 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.
A number of bullet weight and velocity combinations are offered in .45 Super, including a 185-grain (12.0 g) bullet propelled at 1,300 ft/s, a 200-grain (13 g) at 1,200 ft/s, and a 230-grain (15 g) at 1,100 ft/s. as well as other weight/velocities provided by Super Express cartridges and Buffalo Bore, such as 255grain at 1050 ft/s.
Sedalia, Missouri based Starline Brass company eventually began marketing factory manufactured brass casings for the chambering, taking the round out of the obscure wildcat cartridge realm. In addition, Ace Custom .45’s Inc. of Cleveland, Texas trademarked the .45 Super name in 1994 and currently markets factory .45 Super pistols, as well as gunsmith adaptations of .45 ACP pistols, and .45 ACP conversion kits. Texas Ammunition and Buffalo Bore offer factory loaded ammunition which is marketed by Ace Custom and others. The Dan Wesson 460 Rowland will also chamber a .45 Super.
- .45 ACP
- .45 Winchester Magnum
- .460 Rowland
- .45 GAP
- .44 Magnum
- List of handgun cartridges
- 11 mm caliber
- "1911 Hot Rods" Handguns Magazine website. Accessed March 11, 2008.
- "VERSATILITY AND POWER THE ‘45SUPER’ CONCEPT" Ace Custom .45s website Accessed March 11, 2008.
- ".45 Super" Everything Development Company website. Accessed March 11, 2008.
- C.D. Rowsell 2014
- ".45 Automatic" Notpurfect website. Accessed February 25, 2008.
- "Starline Product Information & Descriptions" Starline Brass website. Accessed March 11, 2008.