so i just bought a rock river tactical entry ar15 yesterday. the gun has 5.56 NATO stamped on the barrel and the receiver has 5.56 stamped on it too. the gun store said it's .223. is this true? i know you're not supposed to shoot 5.56 in a rifle that's .223 chamber. i was told to shoot .223 in this rifle. does this sound right?
223 or 5.56
- Thread starter hvychev77
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ChazHollywood
Member
Go by what the barrel says (not what the guy at the gun store tells you). 
But yes, if your barrel is marked "5.56 NATO" then you are good to shoot commercial 5.56 or .223 from that rifle.
But yes, if your barrel is marked "5.56 NATO" then you are good to shoot commercial 5.56 or .223 from that rifle.
sarduy
Member
most people cant tell the difference between a .223 and 5.56 including gun store sellers....
if you have a .556 barrel, you are good to go even if the lower say .223
if you have a .556 barrel, you are good to go even if the lower say .223
http://www.thehighroad.org/showthread.php?t=609827
The .223 Remington is a sporting cartridge with almost the same external dimensions as the 5.56x45mm NATO military cartridge.
The .223 Remington is a sporting cartridge with almost the same external dimensions as the 5.56x45mm NATO military cartridge.
Jeff F
Member
Not always the case. Rugers Mini 14 says cal .223 but is in fact chambered for the 5.56.
Like others have said, if its chambered for 5.56 you can shoot .223 or 5.56.
madcratebuilder
Member
The pressures are not the issue, the amount of leade is the issue.
tyeo098
Member
No.
Pressure is the issue.
Src: http://en.wikipedia.org/wiki/.223_Remington
http://en.wikipedia.org/wiki/5.56x45mm_NATO
Leade differences will only affect accuracy when firing a .223 out of a 5.56 barrel.
How does this affect accuracy, when the two rounds are the same length ?
tyeo098
Member
The rounds are exactly the same dimensions, its the chambering specs and pressure that is different. A longer lead means that the bullet is going down the tube without any rifling for a longer period.
Helotaxi: The bullet doesnt go through a void where it can tumble as it pleases and exit backwards, its still the barrel, there is just not rifling. No chance of yawing.
The extra pressure of the 556 is to account for it engaging the rifling (and slowing it down) sooner.
The longer lead on the lighter 223 is to keep the velocity constant and pressure in check. Its all mechanics.
Despite the slight differences folks have been shooting them interchangebly for years. I've yet to find anyone who has ever experienced a problem. Or even knows an uncle's girl friend, who had a cousins husbands best friend that had a problem.
The amount of potential yaw is miniscule, but it does happen. We're talking several thousandths of runout, but it is enough to get the bullet spinning off its center of mass initially and can lead to some divergence coming out of the barrel. There's a reason that most accuracy shooters try to minimize or eliminate jump to the lands with their rifles.
Nope. The 5.56 has the longer leade and that is to keep the pressure from the hotter loading from getting excessive. Many of the custom .223s with a slower twist have a minimal leade to allow the short varmint bullets to be jammed into the lands or at least touching.
W.E.G.
Member
Its whatever the barrel-stamp says it is, and not what the goob at the gun counter thinks it is.
alsaqr
Member
Had a beautiful .222 Sako re-chambered to .223 in 1968. Since that time i've fired hundreds of thousands of rounds of 5.56mm ammo in my .223 guns: No signs of high pressure-nothing.
If all the myths were true there would be pictures of blown up guns all over the web.
The M16 rifle is a full auto weapon: The longer leade of the 5.56mm chamber is for reliability with dirty ammo. The leade of the 7.62mm chamber is longer than the .308 for the same reason.
Pressure is not the issue. US military 5.56mm ammo is loaded to 52,000-55,000 psi dependng the particular round. See Army TM 43-0001-27; pages 10-3 (M193 ball) and 10-19 (M855 ball).
http://www.hk94.com/hk/topic/26614-...mmunition-data-sheets-for-small-caliber-ammo/
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It is about time somebody got it right, basically there is not a nickels worth of difference between the Rem. .223 & the 5.56x45 NATO, only in the chamber. Alsaqr nailed it, good work buddy.
alsaqr
Member
Believe it or not, i've done just that; no extraction problems at all and no signs of high pressure either.
firemanstrickland
Member
I havent read the other replies but it drives me absolutely insane how all these supposed EXPERTS call all of these rifles .223 and...well, you all know what I mean. I can not stand ignorance. If your rifle is stamped 5.56 then thats what the rifle is chambered in. YES you can shoot .223 out of it and it will perform, just fine. It is good that you asked, I hope you got your answer, and please keep in mind my anger is directed towards the gun shop owner. Good luck.
The shorter leade in the .223 SAAMI chamber will increase the chamber pressure because the bullet engages the rifling sooner. 55k might be the spec pressure for 5.56 (US loaded, the NATO spec for max pressure is actually 62k ish) but that is the pressure for the round in the 5.56 chamber. Change the chamber, change the pressure. Sure the rifle can probably handle the higher pressure but actual pressure testing of 5.56 NATO ammo fired in a SAAMI .223 chamber resulted in pressures in the 85k range.
The good news is that essentially no one cuts a SAAMI spec .223 chamber.
The good news is that essentially no one cuts a SAAMI spec .223 chamber.
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