Don’t be ashamed if you don’t know the differences between 5.56 and .223 ammo. There are experienced shooters out there that are even a little unsure. There are many that assume that the two rounds are interchangeable. Let’s just make it clear how the rounds aren’t interchangeable. Here is a breakdown of how .223 and 5.56 ammo Sacramento are similar, and more importantly, how they are different.

A Brief History

The 5.56 round was first developed near the end of the 1950s. It was originally used as an experimental round for the United State Military. 5.56 was a desirable round as it is a high velocity, small caliber round. It solved the weight and control issues that existed in the 7.62x51mm cartridge that was previously used. In 1963, NATO adopted it as a standard round. Not long after, Remington introduced the .223 as a civilian version.

Case Size

It true that the brass case dimensions for the .223 and the 5.56 are the same. Regardless, this does not make the rounds interchangeable. There are several factors to take inter consideration before determining which round is safe in which firearm.


There is a difference in the distance between the mouth of the round and the pointed where the rifle contacts the bullet. The 5.56 chamber has a longer distance than the .223. As a result, the presser in the chamber when firing is dramatically different.


Because of the difference discussed above, the .223 round produces a lower pressure and is generally safe. But, if a 5.56 is used in a gun chambered for a .223 cartridge there will be a higher pressure than what is considered safe. Overpressuring in the chamber will lead to a host of dangerous malfunctions.

About Redline Ballistics

Do figure out which round is best for the task you wish to perform stop by our store and we can discuss .223 and 5.56 ammo Sacramento more. What type of shooting you prefer and your shooting style will determine which round is best for you. Follow us on Twitter, Instagram, and Facebook for more shooting tips and ammo sales.