AmateurHunter44857

Don't laugh at me when you see the title. I was going through a magazine tonight that listed a majority of the different rifles, shotguns, revolvers and such on the market and they had a ton of AR-15's in there. Under Calibers on a few of them with different calibers they had .22,22-250,.223,5.56mm,.308. I always thought 5.56mm and .223 were the same, am i wrong?

WhitetailsInc.info

The .223 and 5.56 Nato are the same case dimensions however the 5.56 is loaded to higher pressures. You can shoot .223 in 5.56 but don't do the reverse. The Wyld chamber allows both, I don't know if the 5.56 chamber is slightly different to allow extraction under the high pressure.

Pavomesa

There has alreadybeen a few zillion military rounds shot through all sorts of .223 caliber rifles. A little late to be telling anyone don't do it.

AmateurHunter44857

So is one better than the other?

Briman

Ditto that.

skin290

You will probably eventually have problems if you shoot 5.56 in a 223 only chamber, so yes, you should tell people not to do it...

bigbulls

A 5.56mm case wallis thicker than the .223which translates to less case capasity and higher pressuresbut the chamber has a longer throat to keep pressures down in the chamber.

The .223 is loaded to lower pressures and does not have a lengthened throat in the chamber.

If you fire a 5.56 cartridge in a .223 chamber it jacks pressures up and could possibly cause case rupture and/ or cycling problems.

falcon

Here we go again. Which 5.56mm/.223 chamber are you talking about? There are at least ten of them. Strange that SAAMI never said a peep for 30 years. Then when the rounds became wildly popular and all that MilSurp ammo became available, it suddenly became dangerous to shoot 5.56mm ammo in a .223 chamber. There is little or no difference in pressure between US loaded 5.56mm military and .223: The difference is accounted for by the fact that the US military measures pressure at the cartridge neck and SAAMI measures pressure over thecase body.Had my .222 SAKO re-chambered for .223 in 1968 or 69. That gun loves TW 67 military ammo. It has fired thousands of rounds of US military ammo without a bobble.

Would SAAMI lie: Yes, they asked the BATFE to re-do the regulations for manufacture and storage of ammo then lied and whined to high heaven when the agency did exactly what they wanted.

" 5.56mm case wallis thicker than the .223"

Another myth is that US military cases are much thicker than commercial cases. See the link for case weights.

Some chamber specifications, case weights anda whole bunch of other stuff.

http://www.ar15barrels.com/tech.shtml

bigbulls

According to the link you provided there is enough differences in chamber dimensions to warrant not shooting 5.56 in a .223 chamber.

Here is another link that provides some good information and other links with even better information.
http://www.thegunzone.com/556v223.html

Obviously not every rifle will have problems but there are enough that will. But people do what they want to do all the time regardless of what information they have readily available.

Pavomesa

Sure military brass is thicker! Same goes for the 7.62 Nato and 308. All the military stuff is intended for gas operated auto loaders. Sure all this is going to translate to slightly higher pressures in SOME civilian rifles. So what? The point is they are essentially the same animal and maybe this explains why you canpurchase milsurp ammo by the ton. It works. Duh. Has anyone ever blown up their gun with it? Any modern firearm in good condition can certainly handle the slightly elevated pressures.

I wish I had a dollar for every round of it I've shot in both calibers. I would be reading this thread from my private island somewhere.

Tempest in a teacup, gentlemen. Anyone who doesn't want to shoot it is fine with me. The price has been going crazy from supply and demand anyway. Meanwhile I think we can expect another million rounds of 5.56 to be safely fired in America's 223 rifles this year...and the next.