10MM Auto (also known as the 10mm or 10mm Auto) is a semi-automatic cartridge primarily used for self-defense and hunting. It is based on a .40 Smith & Wesson case necked down to accept a .40-caliber bullet. This cartridge was created in 1983 by the legendary firearms expert Jeff Cooper for the FBI. Cooper experimented with numerous ammunition types before becoming satisfied with the 10mm. He believed that the 10mm Auto’s intermediate recoil energy along with its larger projectile size made it superior to other comparable cartridges.
The 10 MM Auto is capable of producing an impressive muzzle energy of up to 500 ft-lbs. The heavier and longer 10mm bullet is able to attain a deeper penetration through the target compared to the .40 S&W cartridge, which may make it better suited for defensive situations. However, the increased recoil and muzzle flip make the 10mm unsuitable for most shooters.
The 10 MM is best used for larger game hunting such as deer, elk, and moose. Its increased penetration power can provide a bigger killing zone than a smaller caliber cartridge such as the 9mm or .45 ACP. The 10mm has also been adopted by some military and law enforcement agencies, such as the US Navy SEALs and the Texas Rangers.
When choosing a 10mm round for defensive purposes, it is important to select an appropriate bullet size. Lighter, low-grain bullets may not produce adequate penetration for self-defense. For instance, the 115-grain bullets–commonly used in the 10mm Auto–may not have the stopping power needed in a defensive situation. Heavier grain bullets, such as the 147-grain JHP, provide increased penetration and stopping power.
When selecting ammunition for the 10mm Auto it is important to take into consideration the barrel twist-rate. This is especially important when using jacketed, or higher-powered, rounds. The twist-rate controls the bullet spin and prevents it from tumbling or yawing, which can lead to inaccuracy and increased recoil. Selecting the wrong bullet weight and twist-rate combination can lead to keyholing, or the bullet not correctly exiting the barrel.
The 10 MM Auto is a powerful cartridge. For this reason it is not suitable for beginners. Its increased recoil and muzzle flip make it difficult to control and can make follow up shots difficult. It is important to ensure the shooter is comfortable with their handgun and are familiar with the cartridge before attempting to use it for self-defense or hunting.