Does .223 Equal 5.56?

[MGMorden]

Problem solved.  just find one marked .223 winchester and shoot whichever you want in it.  

DOH!

I hate it when I do that .  Thanks for the catch.

[SHOOTALL]

Then add the harder primers , less case capacity , and testing in a different way to a higher pressure and a longer leade in chamber it would appear there is some difference on the 5.56. Then add there are hybred chambers and the pratice of some AR's being marked 223 but are safe for 5.56 ( a safety concern by manfactures also some say Ruger mini 14's are chambered this way . It would be wise to check in either case.

[DC]

I commented on this once before but I wasn't entirely accurate.  I had a lengthy conversation with the folks at Ruger
about this recently and this is what I was told.

The manuals for the Mini 14's say that you can shoot both the 556 and the 223 in them with the exception of their more
recent Target Mini 14's.  The target models have a .223 chamber which is very slightly smaller that the chamber on the other Mini's
and most bolt action rifles chambered for the 223 Rem cartridge.  That is not to say that they won't work and the pressure differences
are not so great as to become unsafe.  It just isn't a good idea.  Any rifle that says 5.56 will shoot 223 Rems interchangably with no
loss in accuracy etc.  It is the other way around where you run into problems or potential problems. 

To see for myself what the difference was, I shot 5 rounds of 5.56 rounds in a Savage varmit 223 with the heavy fluted barrel.  Two of the five had flattened primers and three rounds did not eject as easily as the follow up 223's.