The 223 Remington cartridge and its AR-compatible offspring.

The M16/AR15 was originally chambered for the .223 Remington (1962), and since then that cartridge has become the patriarch of several very useful cartridges that are also AR-15 compatible.

Metallic rifle cartridges come in families. In the .30-06 family, you have the .270 Winchester and .280 Remington. In the .308 Winchester family, you have the .243 Winchester and 7mm-08 Remington. Though the .223 Remington now has its own family, it was based on the .222 Remington (1950), which was a proprietary cartridge, meaning it wasn’t based on another SAAMI-approved cartridge.

223 Remington Ammo

If you want an AR-15 that’s multi-cartridge compatible, it makes sense to choose cartridges from the same family. This will allow a conversion with nothing but a barrel or barreled upper receiver. Since the cartridges all come from the same family, you won’t need to replace the bolt carrier or bolt, because the rim diameter for all the cartridges is the same.

With an AR-15 chambered for the .223 Remington, you can do this and run five other cartridges. Here’s a look at the .223 Remington, and the family of AR-15-compatible cartridges it has fathered.

The development of the .223 Remington is intrinsically linked to the M16, which is the full-auto version of the civilian rifle now known as the AR-15, or in more politically correct circles, as the MSR (modern sporting rifle). The military would ultimately replace the .223 Remington with its twin, the 5.56 NATO, but that didn’t have any impact on the cartridge’s popularity. Since its introduction, it has become very popular for competition, hunting and self-defense.

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