The AR-15 is a hugely popular platform, but a common question for both newcomers and experienced shooters is: what caliber does an AR-15 shoot? The simple answer is: it depends. While the .223 Remington/5.56x45mm NATO is the most common caliber, the AR-15 platform's adaptability allows it to fire a surprising variety of cartridges. Let's delve deeper into the specifics.
The Standard: .223 Remington and 5.56x45mm NATO
The vast majority of AR-15s are chambered in either .223 Remington or 5.56x45mm NATO. While seemingly interchangeable, there are crucial differences:
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.223 Remington: This is a commercially produced cartridge with slightly lower pressure than its military counterpart.
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5.56x45mm NATO: This military round has higher pressure, designed for use in automatic weapons.
The critical point: Firing .223 Remington in a 5.56x45mm NATO chamber is generally considered safe (though not always recommended), but firing 5.56x45mm NATO in a .223 Remington chamber is dangerous and can lead to catastrophic barrel failure. Always check your firearm's chambering before loading ammunition.
Why the Difference Matters
The pressure difference between these two cartridges is the key factor. The higher pressure of the 5.56x45mm NATO cartridge can exceed the design limits of a barrel chambered only for .223 Remington, potentially causing damage.
Beyond the Standard: Other AR-15 Calibers
While .223/5.56 is the dominant caliber, the AR-15 platform's modularity enables it to shoot other cartridges with the appropriate upper receiver and barrel changes. These include, but are not limited to:
- .300 Blackout: A subsonic cartridge designed for suppressed use, offering increased stopping power compared to .223/5.56.
- 6.8 SPC: Designed for improved range and penetration compared to the smaller calibers.
- .458 SOCOM: A powerful cartridge delivering significant stopping power for larger game hunting or personal defense.
- .50 Beowulf: A large-bore cartridge offering substantial stopping power, often used for hunting large game.
- 6.5 Grendel: This cartridge is known for its longer range and better ballistic performance than 5.56.
Important Note: Converting your AR-15 to a different caliber requires more than just swapping the upper receiver. You'll likely need a new bolt carrier group (BCG) and magazine, as well as ensuring the correct gas system for optimal functionality. Always consult a qualified gunsmith for any modifications.
Conclusion: Choosing the Right Caliber
The caliber your AR-15 shoots depends entirely on the upper receiver and barrel assembly installed. While .223 Remington/5.56x45mm NATO is the most prevalent, a range of other options offers diverse capabilities for various purposes. Always prioritize safety, ensuring you understand the specifications of your firearm and the ammunition you use. Remember to consult with experienced gunsmiths or firearm professionals before making any modifications to your weapon.
