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What is the Difference Between .223 And 5.56?

What's the difference between .223 and 5.56, if any?

The .223 Remington and the 5.56 NATO have been compared to each other for years, since the production of the 5.56 in the 50s. There are many different views and arguments when discussing these two rounds; their similarities, differences, and most of all, preference.

In 1957, the 5.56 was ultimately created to be tested for a fit for the M16 rifle. Using this particular round with the M16 was meant to produce the ultimate cartridge for military use that would still travel faster than sound at 500 yards.

After much deliberation between military companies and subsidiaries, this cartridge and weapon were both adopted by the United States military in 1964. After the initial shock was over about what an amazing round had been produced, they began to be mass produced for all types of military and security outfits across the country.

The expanding popularity among commercial military use shed new light on civilian defense and sport firearms, leading to the development of the .223 for the average American. With overwhelming confusion of the difference in the two, the .223 round began to make itself known as one of the most popular and reliable rounds in the world.

A slight difference can be made in the chamber of these two guns, leaving the 5.56 just a bit larger than the .223. Also, the pressures with these two rounds are measured very differently, giving another reason for argument among differences. The actual throat in the 5.56 chamber is longer than that of the .223, leaving a substantial margin for argument. That being said, the chamber of the 5.56 is nearly two times the size of the .223 Remington.

This leads to the ultimate question about these two rounds: Can each be shot in the other weapon? A .223 round can be fired in a stable weapon with 5.56X45 mm specs. However, it is not recommended and deemed very unsafe by many to fire a 5.56X45 mm round chambered for the .223 Remington.

Most 5.56 chambered weapons come equipped with the standard 1:7 inch twist for the rifling, making it different than its counterpart with a 1:12 inch twist rate.

Ultimately these two rounds are more similar than different. Making the decision on what you do with your rifles and rounds is a personal decision, but the differences speak for themselves. Although some would call these guns cousins, they are different in various ways, built to specifications of their uses and production.

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Would you choose the .223 or the 5.56? Tell us in the comments. 


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What is the Difference Between .223 And 5.56?