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SAINT
The .45 ACP
The .45 ACP (Automatic Colt Pistol) or .45 Auto is a rimless straight-walled handgun cartridge designed by John Moses Browning in 1904, for use in his prototype Colt semi-automatic pistol.
During the late 19th century and early 20th century, the U.S. Cavalry began trials to replace their sidearm arsenal of issued .45 Colt Single Action Army (SAA) in favor of the more modern and versatile double-action revolver in .45 Colt. After the example of the Cavalry, the Army in turn had fielded versions of double-action revolvers in .38 Long Colt. It was eventually evaluated that the .38-caliber round was significantly less effective in overall stopping-power than the .45 Colt against determined opponents in cases such as the Moro juramentado warriors, who were encountered in the Moro Rebellion. The then-current issue rifle, the .30-40 Krag, had also failed to stop Moro warriors effectively; the British had similar lack-of-stopping-power issues switching to the .303 British, which resulted in the development of the dum-dum bullet in an attempt to compensate for the round's deficiencies.
This experience, and the Thompson–LaGarde Tests of 1904, led the Army and the Cavalry to decide a minimum of .45 caliber was required in a new handgun. Thompson and Major Louis Anatole La Garde of the Medical Corps arranged tests on cadavers and animal remains in the Chicago stockyards, resulting in the finding that .45 was the most effective pistol cartridge. They noted, however, training was critical to make sure a soldier could score a hit in a vulnerable part of the body.
After successful military trials, it was adopted as the standard chambering for Colt's M1911 pistol. The round was developed due to a lack of stopping power experienced in the Moro Rebellion using the .38 Long Colt. This experience and the Thompson–LaGarde Tests of 1904 led the Army and the Cavalry to decide a minimum of .45 caliber was required in a new handgun.
The standard issue military .45 ACP round has a 230-grain bullet that travels at approximately 830 feet per second when fired from the government issue M1911A1 pistol. It operates at a relatively low maximum chamber pressure rating of 21,000 psi (compared to 35,000 psi/241 MPa for 9mm Parabellum and .40 S&W), which due to a low bolt thrust helps extend service life of weapons. Due to standard pressure .45 ACP rounds being inherently subsonic when fired from handguns and submachine guns, it is a useful caliber for suppressed weapons to eliminate the sonic boom.
Drawbacks for military use include the cartridge's large size, weight, increased material costs in comparison to the smaller, flatter shooting NATO standard 9×19mm Parabellum cartridge, which uses less powder, brass, and lead per round. Standard 9mm NATO ammunition has limited armor penetration capability − a deficiency with .45 ACP whose large, slow bullet does not penetrate armor to any great extent. The low muzzle velocity also makes the bullet drop over long ranges, making hits more difficult; however, it is important to note that the vast majority of self-defense situations involving handguns typically occur at close ranges.
Recent testing of the three major police and military calibers by the Federal Bureau of Investigation found that the .45 ACP was no more effective with regard to terminal ballistics than either 9 x 19mm Parabellum or .40 S&W. After two years of testing, one of the final FBI comments was that services that adopt (or stay with) .40 S&W or .45 ACP did so at the risk of increased recoil and a possible reduction in accuracy as 9 x 19mm with premium quality ammunition had nearly exactly the same performance. A factor rated by the recent FBI testing was accuracy and time to recover. The .45 ACP handguns ranked last, largely due to increased recoil. Because of its large diameter and straight-walled design, the .45 ACP geometry is the highest power-per-pressure production, repeating round in existence. This is because of the higher powers achievable with .45 Super, and +P loads. Because of these inherent low pressures of the standard pressure round, however, compensators and brakes have little effect until +P and Super loads are utilized.
Today, most NATO militaries use sidearms chambered for the 9×19mm Parabellum cartridge, but the effectiveness of the .45 ACP cartridge has ensured its continued popularity with large caliber sport shooters, especially in the United States. In 1985, the .45 ACP M1911A1 pistol was replaced by the Beretta M9 9mm pistol as the main sidearm of the U.S. military, which in turn was replaced with the SIG Sauer P320 designated M17 for the full size and M18 for the compact.
The .45 ACP (Automatic Colt Pistol) or .45 Auto is a rimless straight-walled handgun cartridge designed by John Moses Browning in 1904, for use in his prototype Colt semi-automatic pistol.
During the late 19th century and early 20th century, the U.S. Cavalry began trials to replace their sidearm arsenal of issued .45 Colt Single Action Army (SAA) in favor of the more modern and versatile double-action revolver in .45 Colt. After the example of the Cavalry, the Army in turn had fielded versions of double-action revolvers in .38 Long Colt. It was eventually evaluated that the .38-caliber round was significantly less effective in overall stopping-power than the .45 Colt against determined opponents in cases such as the Moro juramentado warriors, who were encountered in the Moro Rebellion. The then-current issue rifle, the .30-40 Krag, had also failed to stop Moro warriors effectively; the British had similar lack-of-stopping-power issues switching to the .303 British, which resulted in the development of the dum-dum bullet in an attempt to compensate for the round's deficiencies.
This experience, and the Thompson–LaGarde Tests of 1904, led the Army and the Cavalry to decide a minimum of .45 caliber was required in a new handgun. Thompson and Major Louis Anatole La Garde of the Medical Corps arranged tests on cadavers and animal remains in the Chicago stockyards, resulting in the finding that .45 was the most effective pistol cartridge. They noted, however, training was critical to make sure a soldier could score a hit in a vulnerable part of the body.
After successful military trials, it was adopted as the standard chambering for Colt's M1911 pistol. The round was developed due to a lack of stopping power experienced in the Moro Rebellion using the .38 Long Colt. This experience and the Thompson–LaGarde Tests of 1904 led the Army and the Cavalry to decide a minimum of .45 caliber was required in a new handgun.
The standard issue military .45 ACP round has a 230-grain bullet that travels at approximately 830 feet per second when fired from the government issue M1911A1 pistol. It operates at a relatively low maximum chamber pressure rating of 21,000 psi (compared to 35,000 psi/241 MPa for 9mm Parabellum and .40 S&W), which due to a low bolt thrust helps extend service life of weapons. Due to standard pressure .45 ACP rounds being inherently subsonic when fired from handguns and submachine guns, it is a useful caliber for suppressed weapons to eliminate the sonic boom.
Drawbacks for military use include the cartridge's large size, weight, increased material costs in comparison to the smaller, flatter shooting NATO standard 9×19mm Parabellum cartridge, which uses less powder, brass, and lead per round. Standard 9mm NATO ammunition has limited armor penetration capability − a deficiency with .45 ACP whose large, slow bullet does not penetrate armor to any great extent. The low muzzle velocity also makes the bullet drop over long ranges, making hits more difficult; however, it is important to note that the vast majority of self-defense situations involving handguns typically occur at close ranges.
Recent testing of the three major police and military calibers by the Federal Bureau of Investigation found that the .45 ACP was no more effective with regard to terminal ballistics than either 9 x 19mm Parabellum or .40 S&W. After two years of testing, one of the final FBI comments was that services that adopt (or stay with) .40 S&W or .45 ACP did so at the risk of increased recoil and a possible reduction in accuracy as 9 x 19mm with premium quality ammunition had nearly exactly the same performance. A factor rated by the recent FBI testing was accuracy and time to recover. The .45 ACP handguns ranked last, largely due to increased recoil. Because of its large diameter and straight-walled design, the .45 ACP geometry is the highest power-per-pressure production, repeating round in existence. This is because of the higher powers achievable with .45 Super, and +P loads. Because of these inherent low pressures of the standard pressure round, however, compensators and brakes have little effect until +P and Super loads are utilized.
Today, most NATO militaries use sidearms chambered for the 9×19mm Parabellum cartridge, but the effectiveness of the .45 ACP cartridge has ensured its continued popularity with large caliber sport shooters, especially in the United States. In 1985, the .45 ACP M1911A1 pistol was replaced by the Beretta M9 9mm pistol as the main sidearm of the U.S. military, which in turn was replaced with the SIG Sauer P320 designated M17 for the full size and M18 for the compact.
