AR15 .223 Rem or 5.56 Nato

[Papa Charlie]

I have been contemplating purchasing a AR15. It is my understanding that one of the two calibers in the title can be fired in the other but not reversed. What is the most universal and which is the cheapest round of the two?

Thanks in advance

 

[Nightraider]

6 of 1, half dozen of another.

Anymore it's a moot point.

 

[SDWhirlwind]

Supposedly the 5.56 chambering has more 'generous' dimensions than .223 Rem. Freebore is 1 for the longer Nato ammo such as 62 gr. So no problems shooting .223 ammo in a 5.56 Nato chamber but possibly issues with using some mil surp Nato ammo in a .223 Rem chamber? I believe shooting any of the 55gr Nato such as M193 will function in most all AR barrels? But I have been wrong many times before! I have 1 Krieger barrel chambered .223 Rem that is quite tight and I have to be carefull what I fire in it. Have grabbed the wrong ammo and left myself with a useless rifle more than once. But it is such a great shooter I can put up with its shortcomings.

 

[Rsadams]

.223 can be fired in a 5.56 chamber but because of the higher pressure of 5.56 you're not supposed to shoot it out of a .223 chamber... You would be hard pressed to find an AR chambered in .223 not a decent one anyway anymore... Most are chambered in 5.56 now...also any "mil-spec" rifles probably will be 1/7 twist most bullets that require that twist won't fit in the magazine...

The 5.56 chamber has a longer lead to deal with the pressure of the ammo that the .233 chamber doesn't have....

Edit... To me it doesn't matter really which I shoot .223/5.56 and I do shoot more .223 in my AR than 5.56.. Since I load for my ARs it's very rare I get into 5.56 pressure and a fast .223 shoots the same to me... Good bullets like in any rifle do make a difference don't expect pin point with factory FMJs for sure.... You will lose some velocity with the 5.56 chamber when firing.223...

 

[jepp2]

What is the most universal and which is the cheapest round of the two?

Cheapest round will be the 5.56 loadings. If you buy Federal XM193 it comes in LC case, but has FMJ bullets, so accuracy can leave something to be desired.

Are you just looking for something to shoot cans with, or something that can shoot groups?

Other chambering options are the 223 Wylde chamber and White Oak Armament offers a custom varmint chamber that you can shoot either 5.56 or 223 in with improved accuracy.

 

[Herzo]

The most common chambering for the AR is the 223 Wylde. It will handle .223 & 5.56 with no problems as to pressure. It is also about as accurate as you can get in the AR platform. Go with the Wylde and don't worry about what you feed it.

 

[Papa Charlie]

My initial plan is to use this for plinking and home protection. I already have my F-Class rifle. I have never heard of the 223 Wylde. Will have to check into that.

Thanks very much for the information and suggestions. I will need to do some more research before I move forward.

 

[XTR]

Pick one

 

[Pawnee Bill]

Same same water buffalo.

 

[Rsadams]

It seems like your getting info here that .223 and 5.56 are the same round.... They are the same if you measure them but they are not the same pressure wise , 5.56 is an over pressure .223.. .223 is rated at 55,000 psi and 5.56 is at 62,350 psi.... As far as which one is more expensive , there the same price basically for your standered 55gr fmj.. Don't shoot 5.56 in a .223 chamber the chambers are different... Once again you will be hard pressed to find a decent AR chambered in .223 anymore... The end of the barrel will be stamped 5.56 , it's easy to tell...

Some reading in the sticky post at m4 carbine.net will tell you exactly what your looking for in an AR and what proper work needs to be done to one especially on the bolt carrier group... They are not all created equal.... Overgassing and improper staking along with inferior metals are the worst enemies to an AR.... All of which can be found on your lower end guns.... If you're buying one to shoot occasionally is one thing... Running one hard like during 1000 round courses during training or depending on one for life threatening situations is different...

I have a nice one and a cheap one and I assure your there's no comparison.... I won't name names to keep people from arguing over it...Just do a little research before you buy , you won't regret doing the research or buying the AR platform.... For instance , the gas key needs to be properly staked with the proper screws that attach it , because if it comes loose you have a single shot rifle... Some companies stamp marks on these screws and the gas key to make them appear to be properly staked but they are NOT properly staked... They spend the time to make it look right but don't do the job right.. It's done to fool people into buying their products at a lower price because the rifles look the same...They are not the same....

Edit... You can shoot .223 in a .5.56 chamber no problem , you will loose a little velocity with the .223 because of the longer lead of the 5.56 but it's not much , not enough to worry about...

 

[mac86951]

So, after extensive research for my AR chambers; here's a quick summary:

Three groups, 223; Wylde; 5.56.

Each group has an off the shelf "Remingtonish" chamber and typically comes in the lower cost items.

Differences in the cartridges for those chambers are primarily the throat and leade. Ranking short to long leade; 223, Wylde, 5.56. what does that do? Gives more clearance for longer bimetal projectiles; and is more pressure forgiving. My understanding of it is a 5.56 in a .223 chamber is really like shooting a hot load that is jammed into the lands.

If you want to shoot a 223 with any off the shelf ammo; I'd recommend a Wylde chamber. Longer throat and more accurate leade angle makes it accurate for a large variety of ammo. A 1:8 would be great for that
If you're going for surplus ammo; 5.56 and a 1:7. Accuracy can be great with handloads, best of luck with the surplus ammo, but I've seen them work well sometimes.
If you really want to keep below a 69gr; I'd recommend a 223 chamber and loads 35-70gr with a 1:9.

Additionally all three have "match" chambers where the case size is adjusted for various brass, tolerances. I don't typically recommend one of those for an AR unless you really like making your own ammo.

A great resource on those chambers are the service rifle folks. White Oak Armament, Keystone Accuracy? And Compass Lake really have it nailed.

Lots of great info above!

I suppose the next question is:. What do you want to do with your AR?

-Mac

 

[Papa Charlie]

Great information guys. Thank you.
As I stated earlier, the primary use is for plinking and home protection. I have my competition rifle.
Of course as with most of my rifles, I eventually try to close the groups, but that is down the road.

 

[Richard Coody]

This is some interesting information .223 vs 5.56.

5.56 vs .223 – What You Know May Be Wrong

https://www.luckygunner.com/labs/5-56-vs-223/

 

[Ned Ludd]

This is some interesting information .223 vs 5.56.

5.56 vs .223 – What You Know May Be Wrong

https://www.luckygunner.com/labs/5-56-vs-223/

Good read, thanks for posting, Richard. However, after going through it, I still have one question for which I seemingly haven't as yet found the answer. If the rated MAX pressure for 5.56 is 62,350 psi, but only 55,000 psi for .223 rem, how is a rifle designated for 5.56 ammunition designed differently (if at all) to accommodate the higher pressure?

I understand the 5.56 chamber dimensions may be slightly more generous. However, this would function to lower the pressure in a 5.56 chamber if anything, not raise it. I also understand that designated 5.56 rounds may be loaded to higher pressure. But that doesn't explain how 5.56 rifles are designed any differently (again, if at all) to withstand the higher pressure. There was mention of gas system changes, but I'm actually more interested in bolt rifles as I'll explain.

The primary reason I'm asking this question is to determine whether the brass itself may be part of the equation. Using brass with a thicker webbing and/or a harder brass composition might be one way to increase the pressure rating for 5.56 ammo without having to modify the rifle itself. If so, I'm wondering whether it is possible to buy such brass. I run loads in .223 Rem F-TR bolt rifles with Berger 90 VLDs. With Lapua, brass life is not so great; the primer pockets loosen up after only a few firings. Years ago, I purchased 1000 pieces of virgin Lake City brass, having heard anecdotally that that it might withstand pressure a little better than Lapua. However, the Lot# of Lake City brass I purchased has some issues including noticeable variance in case wall thickness and it require far more effort to uniform the primer pockets/flash holes. In my hands, the precision was not equal to what I expect from Lapua brass. Yet I find myself wondering whether someone makes very high quality 5.56 brass that might be a suitable replacement for Lapua that will last a little longer. I understand that reducing the loads I use is one way to alleviate the issue. However, running a .223 Rem in F-TR already puts one at a slight ballistic disadvantage and reducing the loads significantly would further increase that disadvantage. The pressure of the load I'm using is predicted by QL to be approximately 57K psi, so it is definitely higher than SAAMI MAX for .223 Rem, although I would not consider it so high as to be "unsafe" as I have used it for many years. I'm just wonder whether there may be a 5.56 brass out there that could do a better job.

 

[Liven The Dream]

I have been contemplating purchasing a AR15. It is my understanding that one of the two calibers in the title can be fired in the other but not reversed. What is the most universal and which is the cheapest round of the two?

Thanks in advance

I can give White Oak Barrels a three thumb's up.
Just put two AR's together with White Oak SS Scope Barrels 24" std. Gas System and 26" Gas System moved 2" forward.
I have Cleaned a 600 yard F-Class Target with ea. Hand loads 80gr. Nosler and 75Gr. Hornady .

 

[kevinbritvec]

White Oak Armament chambers all of their barrels in .223 Wylde and they continue to amaze me every time I buy one. Never had a dud in twenty plus years. 1/7 or 1/8 won't matter. Their Predator barrels are the perfect weight for a varmint or accuracy rig without being a boat anchor. Their SPR barrels are perfect for self-defense or action shooting. I would never recommend anything heavier than their service rifle barrels simply because of weight. They make world class barrels at a mid-range price point.

 

[ronemus]

The .223 Remington is rated at 55k CUP (measured with a copper crusher, not psi) while the 5.56 is 62k psi (piezo pressure measurement); the two are actually much closer than the numbers would indicate. However, the 5.56 leade is longer and max loads developed for it may be overpressure in a .223 chamber.

 

[jelenko]

Ned - Modern rifle actions will handle the NATO level pressures. So, the 'difference' is just in what chamber is used.
I've heard that some older actions would handle only the lower, SAAMI 223 level pressures.
For example, the ONLY difference in a rifle used for service rifle high power competition is the chamber. For rifles barrelled for 224 bullets, the vast majority are chambered in either Wylde, Compass Lake's 'cle' chamber or Nato 556.
One could have the barrel chambered in 223 and just use the lower pressured 223 rounds.
I don't know enough about older rifles to give an example of one that would only handle the lower SAAMI 223 pressures.

 

[Ned Ludd]

The .223 Remington is rated at 55k CUP (measured with a copper crusher, not psi) while the 5.56 is 62k psi (piezo pressure measurement); the two are actually much closer than the numbers would indicate. However, the 5.56 leade is longer and max loads developed for it may be overpressure in a .223 chamber.

I decided to look the figures up for myself:

According to SAAMI specs, .223 Rem Maximum Average Pressure (MAP) is 52,000 CUP or 55,000 psi (see reference pgs. 14 and 26: https://saami.org/wp-content/upload...99.4-CFR-Approved-2015-12-14-Posting-Copy.pdf ).

According to NATO, which uses EVPAT testing methods, maximum pressure for the 5.56 is 62,366 psi (reference: https://en.wikipedia.org/wiki/5.56×45mm_NATO).

According to the U.S. Military SCATP methods, which are based on those used by SAAMI, the maximum pressure is 55,114 psi (reference: https://en.wikipedia.org/wiki/5.56×45mm_NATO).

So the bottom line is that MAX pressure for the .223 Rem and and 5.56 are NOT different to an extent worth discussing when the same measurement system is utilized (55,000 psi vs 55,114 psi). That is not to say that 5.56 rounds by virtue of the differences in how they are loaded couldn't generate higher pressures in a .223 Rem chamber, which is apparently what the whole debate is about. Nonetheless, I get it now: the differences between the two cartridges/chambers do NOT involve using a stronger action or thicker/harder brass. It's analogous to what might happen if you loaded up any other cartridge with a charge weight near MAX and proceeded to seat the bullets .025" into the lands (jammed), which might create a pressure spike upon ignition and/or an over-pressure issue. In other words, a factory .223 Rem rifle throated long would fire 5.56 rounds with no pressure issues. In my mind, it is NATO's use of a different measurement system that lists the 5.56 MAX pressure at well over 62,000 psi that is the root cause of many of the common misperceptions about differences between the two.

 

[jelenko]

Interesting - and confusing.
From the "556 X 45 NATO" reference: "Differences in testing methodology have led to widespread confusion, however when measured with identical measuring equipment using identical methodologies, .223 Remington yields peak average pressures about 5,000 psi lower than 5.56 NATO"