# Coonverting 5.56 to .223



## macker13 (Nov 7, 2006)

I'm planning to build an AR an have been doing a bunch of research. I'm not trying to start yet another .223 vs 5.56 debate. Rather, I had a thought that I wanted to throw out for your discussion.

I know that you can shoot .223 in a 5.56, but not the reverse due to the bullet of the 5.56 being jammed against the lands since this causes a dangerous pressure spike. As I've gone throught this, I had a question. Has any one convereted 5.56 loaded rounds to .223 by simply running the 5.56 ammo through a seating die and seating the bullet to .223 specs?

Before anyone starts the flames, I'm planning to load the majority of my own, so this is not really an issue for me, just a case of curiosity.


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## farmerj (Jun 19, 2004)

look at putting a wylde chamber into it then.


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## Stella1 (Jun 20, 2011)

223 Remington vs. 5.56x45--Chambering and Throat Considerations
Is the .223 Remington the same as the 5.56x45? The answer is yes and no. There ARE differences between the .223 Remington as shot in civilian rifles and the 5.56x45 in military use. While the external cartridge dimensions are essentially the same, the .223 Remington is built to SAAMI specs, rated to 50,000 CUP max pressure, and normally has a shorter throat. The 5.56x45 is built to NATO specs, rated to 60,000 CUP max pressure, and has a longer throat, optimized to shoot long bullets. That said, there are various .223 Remington match chambers, including the Wylde chamber, that feature longer throats. Military 5.56x45 brass often, but not always, has thicker internal construction, and slightly less capacity than commercial .223 Rem brass.

Since you be building your AR the best course to take is to get a barrel that is chambered for 5.56 unless you will be getting into to service rifle competitions heavily then maybe the wylde chamber would be something to look into. If you are building this for basic range shooting and what not then a chambering for 5.56 will be fine. That is what I did when I built mine so I don't have to worry about ammo issues.


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## People (Jan 17, 2005)

That is not a good idea. The gov standard is about 60,000psi from a standard 5.56 chamber. Individual rounds are allowed to measure 70,000psi. Just jamming the bullets back will not solve the problem of excessive pressure. It may cause more problems as most gov ammo is crimped pretty well.

If you want to shoot Gov type ammo then you will need a different chamber.

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