5.56mm NATO versus 223 Remington Chamber Differences

[BlackRifleMedic577]

New to the site. Good thread!! Thanks for the info.

[hunt_ak]

Tagged....

Thanks, Molon!!

[donwalk]

also...one should keep in mind that once fired in a 5.56 chamber, the .223 is 'fire-formed' to the 5.56. that in turn alters the water capacity of the case...ever so slightly, but the brass should be kept separate for re-loading purposes.

different primers and a 'hot' load could result in a spike in pressure.

[markm]

also...one should keep in mind that once fired in a 5.56 chamber, the .223 is 'fire-formed' to the 5.56. that in turn alters the water capacity of the case...ever so slightly, but the brass should be kept separate for re-loading purposes.

different primers and a 'hot' load could result in a spike in pressure.

Huh? Chamber dimensions are THE SAME. The cases don't touch the leade which is where the two differ.

[donwalk]

i saw an article and diagram, where the case shoulders differ slightly in angle.

at the moment i cannot recall...i will research the article and see if i can recover it. (the article)

[markm]

Ok. I was just looking at the pic above where it says chamber dimensions are the same. I'd think that a resizing die is going to bring the brass back to the same size regardless though.

[slomo]

If the only difference between 5.56 Nato and .223 Rem chamber is the leade and freebore then why is the allowable headspace greater with 5.56 Nato?