5.56/.223 question

[longshanks94]

I have some questions regarding some things I remember reading a while back but would like advice or confirmation.

First off, should I shoot 5.56 or .223 out of an AR15? I know they are basically the same, but is there any difference that gives one the edge over the other? I saw in Academy that they had .223 cheaper than the 5.56.

Also, once I start shooting either one, should I stick to it and not use the other except in emergencies?

Finally, the only uses for my AR will be plinking and self defense.

Thanks, I hope I've been clear enough in asking these questions.

[Oysterboy]

It won't matter which you shoot but the 556 is stronger than the 223 and depending on whether your AR15 is made to chamber 556 I wouldn't shoot the 556 if it's only chambered for 223.

[pilpens]

5.56 (NATO) is a higher pressure round than .223.
5.56 chamber is slightly different than .223 chamber.
If your AR is chambered for 5.56, then it is safe to shoot both 5.56 and .223.
If your AR is chambered for .223, then shoot only .223.
If your AR has Wylde chamber dimension, it can safely handle both .223 and 5.56

AR barrels are normally stamped with the cartridge/chamber it is made for.

See:
http://bearingarms.com/223-remington...ould-hurt-you/

On a .223 Remington spec rifle, the leade will be 0.085”. This is the standard described by the Sporting Arms and Ammunition Manufacturers’ Institute, Inc. (SAAMI). The leade in a 5.56 NATO spec rifle is 0.162”, or almost double the leade of the .223 rifle.

A shorter leade in a SAAMI spec rifle creates a situation where the bullet in a 5.56 NATO round, when chambered, can contact the rifling prior to being fired. By having contact with the rifling prematurely (at the moment of firing), chamber pressure can be dramatically increased, creating the danger of a ruptured case or other cartridge/gun failure

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[longshanks94]

Thanks for the great replies. My AR is chambered for 5.56. I'll probably stick with that since I prefer a hotter round.

[marine6680]

Cheaper plinking ammo is always a good thing, so don't feel you need to stick with one or the other only.

A good round with the performance and characteristics you want is what you should use, whether it's 223 or 556.


I seen some testing results recently that compared 223 and 556.

The specs used to test 223 to Sami standards and those used to test 556 are not comparable... They use different methods of checking pressures and different units of measure.

From the testing they showed that 556 was indeed higher pressure, but not as high as many people thought.

They also tested 556 in a 223 chamber, and they did note increased pressures, but nothing drastic, it was only a percent or two.

This is limited testing, and should be looked at as only a data point.

The safest answer is avoid 556 in a 223 chamber.

But being a 556, you will not have issues with your AR.

[bfoosh006]

Bear in mind hotter isn't always better....

Fed. .223 50gr Tipped Varmint shoots FAR more accurately then its price point should allow... It is not a round I would use for any form of serious business... just for tiny groups.

Slightly larger groups then Fed. Gold Medal Match out of my rifles at 100 yards.

Just over 1 MOA is the norm...

http://palmettostatearmory.com/index...0/category/53/

[Theohazard]

I'll add that it's rare to find an AR-15 (or other semi-auto rifle) that's truly chambered in .223. Some manufacturers put ".223" on the box or even on the receiver, but the barrel is marked "5.56" so that's what it's actually chambered in.

And if you have a rifle that's truly chambered in .223, you can probably still get away with shooting 5.56 out of it. Just keep in mind that a 5.56 fired out of a true .223 chamber can produce chamber pressures that are higher than recommended, so it's not really a great idea.

[rickyrick]

Most cases, decent .223 shoots better than 5.56. As stated above, hunting ammo performs better for me. Plinking doesn't really matter. I've had some good luck with OTM as well.

Not that 5.56 ammo is that bad out of an AR anyway.

[James K]

"By having contact with the rifling prematurely (at the moment of firing), chamber pressure can be dramatically increased ..."

I have seen that information repeated many times, and simply do not believe it. For many years, gunsmiths (including the undersigned) chambered barrels for best accuracy by making sure that the bullet was touching or even into the rifling, in other words, zero leade. No significant pressure rise was ever an issue or, IIRC, even discussed.

Now we are told that in the AR-15 a short leade will cause a pressure rise so great that the rifle will explode like a 100 kt nuke and wipe out the county. Sorry, but I just don't think that is true.

Besides, the short lead is pretty insignificant. Bullets are not solid tool steel. At .223 pressures, the bullet acts like is was made of silly putty and will conform to about any shape the barrel has.

Jim

[bfoosh006]

James K .... no offense intended at all... but firing 5.56 in a .223 chamber can lead to higher then normal pressures.

IMHO... and given the large differences in chambers, leades and free bore...it is easier just to be aware of possible issues with 5.56 fired in a .223 chamber.

BTW... I have one of those .223 marked Colts and it is actually chambered in 5.56 with a really long throat. Long enough to fire Fed. 80gr OEM loads.

Again darn near everyone uses a different free bore, leade and throat... so just be careful.

Images from Molon....





Image from this thread on .223 v. 5.56 Chambers....

http://www.m4carbine.net/showthread....er-Differences

I, personally can think of numerous 5.56 factory rounds that I do not feel are safe in a steep leade, short throated, short freebored .223 chamber.

Again no offense intended, and most every rifle will probably have a different "chamber" cut in it.


http://www.radomski.us/njhp/cart_tech.htm

So do please be careful if you decide to fire 5.56 in a .223 chamber, and be aware that you "can" cause unnecessary over pressure.

I have always felt that the gas operated AR15's system will "mask" some of the pressure issues.... but I still heed the warning about 5.56 in a .223 chamber.

I know there are two sides to this train of thought.... ( http://www.luckygunner.com/labs/5-56-vs-223/ ) ...but do want to point out, in extremes, it is very probable you will have issues.

[Adamantium]

Thanks for the great replies. My AR is chambered for 5.56. I'll probably stick with that since I prefer a hotter round.

In a 5.56 chamber, where there is no chamber pressure concerns, there is very little to gain by shooting most 5.56 pressure ammo. I've seen it discussed online in a variety of ways, IE; that's what the rifle was designed to shoot, for increased reliability, because that's what the "serious shooters" use, etc. As an experienced shooter, I honestly can't think of any one AR related topic that is more overrated than placing importance on 5.56 plinking ammo. And that is saying a lot, as there are many things which are overrated in the AR world.

For the military, there is an advantage. From the time when the AR was adopted to very recently, the 5.56 has been handicapped by ineffective bullets which are 100% reliant on velocity to perform effectively. But no such situation exists for civilian shooters. In fact, almost all effective SD ammo is 223 pressure. For target shooting, the extra bit of velocity isn't helping either, as the bullets used aren't accurate enough at ranges where 223 velocities fail. Also, no rifle is gassed so that it will only shoot 5.56 pressure. Colts/DD/BCM/LMT/whatever all shoot standard pressure 223 without problem.

The only thing that affordable 5.56 pressure ammo does for the civilian shooter is add wear and tear on to the gun.

[longshanks94]

Originally Posted by Adamantium

In a 5.56 chamber, where there is no chamber pressure concerns, there is very little to gain by shooting most 5.56 pressure ammo. I've seen it discussed online in a variety of ways, IE; that's what the rifle was designed to shoot, for increased reliability, because that's what the "serious shooters" use, etc. As an experienced shooter, I honestly can't think of any one AR related topic that is more overrated than placing importance on 5.56 plinking ammo. And that is saying a lot, as there are many things which are overrated in the AR world.





For the military, there is an advantage. From the time when the AR was adopted to very recently, the 5.56 has been handicapped by ineffective bullets which are 100% reliant on velocity to perform effectively. But no such situation exists for civilian shooters. In fact, almost all effective SD ammo is 223 pressure. For target shooting, the extra bit of velocity isn't helping either, as the bullets used aren't accurate enough at ranges where 223 velocities fail. Also, no rifle is gassed so that it will only shoot 5.56 pressure. Colts/DD/BCM/LMT/whatever all shoot standard pressure 223 without problem.





The only thing that affordable 5.56 pressure ammo does for the civilian shooter is add wear and tear on to the gun.

Thank you. That's very insightful.

[Oysterboy]

Most AR types are over gassed to ensure recycling.