.223 Remington / 5.56x45mm Ammo

.223 Remington and 5.56x45mm NATO are two very similar cartridges that are often used interchangeably in firearms. While they have similar dimensions, they are not identical, and it is important to ensure that the correct ammunition is used for each firearm.


The .223 Remington cartridge is a rimless, bottlenecked rifle cartridge that was introduced by Remington in 1964. It is typically loaded with a 55-grain bullet and has a muzzle velocity of around 3,240 feet per second. The .223 Remington cartridge is primarily used in civilian and law enforcement applications for target shooting, varmint hunting, and self-defense.

The 5.56x45mm NATO cartridge is a rimless, bottlenecked rifle cartridge that was developed by the United States military in the 1960s. It is typically loaded with a 55-grain or 62-grain bullet and has a muzzle velocity of around 3,100 to 3,300 feet per second. The 5.56x45mm NATO cartridge is used by militaries around the world for a wide range of applications, including combat and training.

While the two cartridges are similar in appearance and function, there are some important differences. The 5.56x45mm NATO cartridge has a slightly longer throat and a higher chamber pressure than the .223 Remington cartridge, which allows it to achieve greater velocity and energy transfer. As a result, firearms that are designed to fire 5.56x45mm NATO ammunition can typically also fire .223 Remington ammunition, but firearms that are designed to fire .223 Remington ammunition may not be able to safely fire 5.56x45mm NATO ammunition.

Overall, both the .223 Remington and 5.56x45mm NATO cartridges are popular and versatile rifle cartridges that are widely used for a range of shooting applications.

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