The .45 ACP (Automatic Colt Pistol) and .45 Colt (also known as .45 Long Colt) are two distinct handgun cartridges with different histories, characteristics, and applications. Here are the key differences between them:
.45 ACP (Automatic Colt Pistol):
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Origin: Designed by John Browning, the .45 ACP was introduced in 1905 for use in the Colt Model 1905 and later the Colt Model 1911 semi-automatic pistols. It was developed for military use, primarily the M1911 pistol.
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Cartridge Type: The .45 ACP is a rimless, semi-rimmed, or half-rimmed cartridge, depending on the specific variant. It uses a straight-walled case with a small rim at the base.
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Bullet Diameter: The .45 ACP uses a .451-inch (11.45mm) diameter bullet.
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Pressure: The .45 ACP typically operates at moderate pressures suitable for semi-automatic pistols.
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Common Uses: The .45 ACP is widely used for self-defense, law enforcement, and competition shooting. It is known for its stopping power and has a long history of military service.
.45 Colt (or .45 Long Colt):
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Origin: The .45 Colt was introduced in 1873 for use in the Colt Single Action Army revolver, also known as the "Peacemaker." It was originally a black powder cartridge for use in single-action revolvers.
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Cartridge Type: The .45 Colt is a rimmed cartridge, designed for use in revolvers. It has a case with a pronounced rim at the base.
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Bullet Diameter: The .45 Colt uses a .452-inch (11.48mm) diameter bullet.
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Pressure: There are two pressure levels associated with .45 Colt ammunition:
- Standard Pressure: Traditional .45 Colt loads operate at relatively low pressures and are suitable for use in older, weaker firearms, including antique revolvers.
- .45 Colt +P: Some modern loadings of .45 Colt ammunition, designated as "+P" (or "Ruger-only" loads), operate at higher pressures and are designed for use in stronger, modern revolvers like those made by Ruger. These loads offer increased performance compared to standard pressure .45 Colt.
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Common Uses: The .45 Colt has a history rooted in the Old West and is commonly associated with single-action revolvers. While it is still used for cowboy action shooting and hunting, it is not as prevalent in modern self-defense and law enforcement applications as the .45 ACP.
In summary, the .45 ACP is a modern, semi-automatic pistol cartridge developed for military and self-defense purposes, known for its widespread use in handguns like the 1911. The .45 Colt, on the other hand, is a historic, rimmed revolver cartridge with a strong association with the Old West and cowboy action shooting. While both cartridges share the same bullet diameter, they are designed for different firearm types and have different pressure levels and historical backgrounds.