5.56 or 223

they are interchangeable, i believe the 5.56 military chamber has a slightly longer throat. If im wrong feel free to correct me. either round will shoot good in either chamber.-so im told
 
Some say you shouldn't but I have fired a lot of 5.56 in any number of .223 Remington chambered rifles and have never had any issues whatsoever. I haven't found most 5.56 ammo to be quite as accurate as most good factory .223 and because it's all been fmj I wouldn't consider it for hunting.
 
They are loaded to different pressures and are not interchangable. You can shoot 223 in a 556, but vice versa is at your own risk. You can probably (many have) get by with it for a while, but you are rolling the dice.

Google ammo oracle.
 
I have a R15, they are chambered for .223 only. Most AR's will shoot either and are stamped on the lower "5.56/.223". The R15 does not have that on the lower. On the barrel it says .223. I will not shoot 5.56 in mine. There's no advantage of shooting 5.56 anyway. .223 ammo is just as cheap as the 5.56 stuff.
 
Remington reps say do NOT shoot 5.56 in the R15. Its chambered only for the .223 commercial round. BBL is stamped .223, lower is not stamped since you can swap uppers that do take the 5.56 & .223, or a .204 upper etc.
The 5.56 has a longer throat to handle the 5.56 pressures and what not, there is a difference.
 
This subject has come up here many, many times.

I've fired 1000's of 5.56 rounds thru several of my 223 AR's and never had a problem. The only extractor I ever damaged was on my 243WSSM and I was really pushing the loads when it spiked and chipped the extractor lip.

The AR has a very strong lock up design and will handle a lot of pressure.

The Remington Rep advises against it and for good reason, they want you to purchase their factory high dollar ammo, that's how they make money.
 
Quote:
they are interchangeable, i believe the 5.56 military chamber has a slightly longer throat. If im wrong feel free to correct me. either round will shoot good in either chamber.-so im told


the 5.56 is also a much higher pressure...the chambers are different, the 556 does have a longer throat, and the cartridge itself has a slightly longer neck. you can put .223 down a 5.56 all day long, but be careful going the other way
 
I wouldnt do it unless it is stamped on the barrel, 5.56/223. It is not worth it. All military spec guns that can shoot both will be stamped.
 
OK...."IF" 5.56 NATO ammunition was safe to shoot in your .223-chambered firearm, I have never understood why you would even consider it anyway?.....

(a) Any military ammo that you would use is going to be FMJ and therefore unsuitable (and unsafe) for hunting.

(b) Using military ammo for "practice" is not going to help your accuracy when you go hunting with your .223 loads, so why bother?

(c) If you're only interested in "burning powder" then wouldn't the bulk .223 ammo that is available from Cabelas and other locations a better choice since it actually fits your chamber properly?...And in those quantities wouldn't it be lucrative to reload your own?

Sorry....I just don't understand why you'd take the risk of damage to your weapon (or yourself) when there are far better options available. /ubbthreads/images/graemlins/confused1.gif
 
I really don't understand why 5.56 NATO ammo would be "unsafe" in a .223 chambered AR, either.
They both use the same barrel blanks and bolt.
The 5.56 NATO is small-base sized, so it's going to chamber loose in either one.
Other than the 5.56 only being available in FMJ, I don't see the problem. /ubbthreads/images/graemlins/confused1.gif

If you've got a bolt gun chambered in .223, all bets are off.

You guys are aware there are such things as "proof" rounds, correct? /ubbthreads/images/graemlins/crazy.gif

Quote:
Each weapon and component considered vulnerable to the effects of a rapid change in pressure, for example barrels, breech blocks and bolts, will be tested by firing one dry round at a corrected minimum of 25% over pressure and one oiled round at a corrected minimum of 25% over pressure. 25% over pressure means 25% in excess of the Service Pressure (Pmax). The Service Pressure is defined as the mean pressure generated by the Service Cartridge at a temperature of 21°C. Such a high pressure proof is conducted with both the weapon and ammunition conditioned to an ambient temperature of 21°C.

Each weapon will be individually tested, from an ammunition lot that produces a minimum corrected mean chamber pressure in accordance with the table below:[1]

Corrected Proof Pressure Requirement (Service Pressure (Pmax) + 25%)
5.56 mm (5.56x45mm NATO) Designed to chamber NATO ammunition Service Pressure Pmax (MPa / (psi) 430 / (62,366)
Proof Round Pressure Requirement (MPa / (psi) 537.5 / (77,958)
Pressure recorded in NATO design EPVAT Barrel with Kistler 6215 Transducer or by equipment to Commission Internationale Permanente pour l’épreuve des Armes á Feu Portatives (C.I.P.) requirements


 
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The only reason really I can think of to shoot the 5.56 Mil surplus ammo is for tactical training or just plain blasting ammo on the cheap, of course I geuss none of it is cheap these days. I agree when hunting, one should use a quality soft point or hp round to do the work. Shooting tin cans with fmj is the only way I would consider using it these days.
 
Well, I used a couple boxes of the .223 FMJs to get my AR on paper when I mounted my new scope and EOTech, and to zero my irons.
It was $3.98 a box a couple years back.
I save some for that kind of situation.
 
Quote:
A couple of BOXES to get it on the paper?



Yeah, to get the Nikon, EOTech and BUIS all zeroed, it took a couple of boxes. I guess I should have said zeroed, not "on the paper".

Sorry.
 
The technical reason for not using 5.56 in .223 is the neck can get pinched
in the throat and therefore pinch the bullet, spiking pressures way above
specs for the military round. Winchester has a good article on it if I remember
correctly. Ar15barrels.com has a good diagram of all the various chambers.
The wylde that rra and other builders use safely shoots both.
 
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But afterwards....did you actually have it "zeroed"? Are you going to hunt with these loads? Before you go hunting, doesn't that practice require another trip to the range and more wasted ammo getting the rifle back to zero with the hunting loads? And after you zero with the hunting loads, do you have to re-zero when you shoot the NATO loads again? (thus wasting even more ammo)

I'm not picking at you Mark, but I shoot as much or more than the "average" guy and I can't honestly think of any instance where shooting NATO ammunition would have saved me any money. Granted, I do reload, and if I didn't I might look at this in a little different light.
 
Quote:
the neck can get pinched
in the throat



The bolt wouldn't go into battery. I'll bet money on it. /ubbthreads/images/graemlins/wink.gif
 
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