It’s one of the most iconic rounds of all time. The 45 Auto, or 45 ACP (Automatic Colt Pistol), was designed by John Moses Browning in 1904. At the time, Browning was working on a prototype Colt semi-automatic pistol, primarily for military purposes. The hope was that the rimless straight-walled cartridge would produce more stopping power than the 38 Long Colt.
Initial testing of Browning's M1911 pistol was positive, and on March 29, 1911, the cartridge became the standard for the U.S. military. The first 45 Auto military rounds were 230-grain full metal jacket cartridges with a muzzle velocity of 830 fps, and these rounds proved effective in the M1911AI pistol, which became the new government-issue sidearm.
The cartridge’s low chamber pressure rating of 21,000 psi was equally pleasing for Browning and the military. It created a low bolt thrust, which extended the longevity of government-issue handguns and machine guns.
Off To War
After World War I started on July 28, 1914, the demand for 45 Auto ammo and the 1911 skyrocketed. Smith & Wesson and Colt were forced to boost large-frame revolver production to keep up with not only the military needs but citizens who were clamoring to buy the 45 Auto.
Interestingly, after the war, Peters Cartridge Company produced a 45 Auto round with a thicker rim and dubbed it the 45 Auto Rim. Ballistically and dimensionally, it was identical to the original cartridge minus the rim design and can only be fired in revolvers chambered for 45 ACP.
By the mid-1980s, the M1911A1 pistol was replaced with a Beretta 9mm, and the 9mm Luger cartridge became the new standard for the U.S. military. However, the 45 Auto had already written itself into the pages of shooting history, becoming a cherished cartridge for both self-defense and sporting, as well as one trusted by law enforcement agencies worldwide.
The biggest reason for the 45 Auto’s success is its overall effectiveness. Over time, as new 45 Auto loads popped up, it became clear that bullets like Speer's Gold Dot Handgun Personal Protection 45 Auto loaded with a 230-grain Gold Dot hollow point traveling at 890 fps, would create devastating results on impact. When a person finds themself in a life-or-death situation, they want a handgun that will drop the bad guy in the blink of an eye, and the 45 Auto delivered.
Another hat-tipper for the 45 has always been its accuracy, especially when fired from a large-frame revolver like the ultra-popular 1911. The heft of the gun keeps muzzle flip down, and the balanced platform allows for remarkable accuracy, which is paramount in self-defense. Shooters looking to hone their skills opt for target loads like Speer Lawman, which uses a TMJ bullet for both economical and realistic performance at the range.
Many who pursue big game in the rough country of the West, where grizzly bears, mountain lions and other predators lurk, also tend to favor the 45 for its accuracy and stopping power.
Around For Good
Some things never go out of style, and the 45 Auto is one of those cartridges. Factory ammunition is ultra-diverse and often, the biggest chore for those who shoot a 45 is walking down the ammo aisle and making a decision.