Quality of the barrel is the biggest factor. Barrels rated 5.56 rather than 223 are rated for higher pressure loads but probably have a longer lead ahead of the chamber. Another factor is twist. 1: 14 1:12 1:10 1:9 1:8 1:7 What bullet weight range do you wish to shoot? Under 52, 55, 65, 70, 75, Up to 90?

Most will say that military ball is not as accurate as good handloads. Well that means with 223 dies

 

You are standing at the entrance to a rabbit hole. If you enter, you may never return.... you have been warned.


Similar to the above statements, I would say matching the ammo to the specific chamber/barrel and with the desired use would be the important factor. If you used rounds of the same spec, there shouldn't be much difference if any that you can easily notice.

You can find lengthy debates all over the internet about this stuff, but the reality is that in most cases just matching the overall package is going to work.

 

Ja, I understand I need to test with my setup. The main reason I ask - before I start buying ammo to test, should I eliminate .223 as my rifle is chambered for both?

It's not cheap or easy to come by these days, and I have a relatively short timeframe.

 

My advice would be to research the specific combo you have and desired use. Chamber type is IMHO not a huge issue. If you have a 5.56 or hybrid type chamber it simply opens up your options. Barrel twist rate, length, distances you intend to shoot at, what you are shooting at, weather conditions, etc.... all with factor into what ammo would be preferred for use regardless of the caliber.

The round most accurate on a windless day at short range will probably not be the round with more knock down power for hunting on a crappy day. At some point punching paper is good, but at other times accuracy just needs to go into the acceptable category with all factors combined.

With the current ammo shortages, you could hopefully find your preferred types of ammo without wasting money on ammo not appropriate for the task at hand.

As a quick/easy example. If you are shooting at closer ranges, but with primitive iron sights, high end match grade ammo might not be worth the extra coin. The reason being that the sight quality would limit overall accuracy regardless. You could compromise more and probably not notice as much.

If you have a great scope, skillset, and longer distances, you might more readily notice better ammo choices.

Give us some details on your rig and intended use, and hopefully you might find someone with specifics on some of your equipment and their findings.

 

Read this

https://www.hornadyle.com/resources...o-and-223-rem-ammunition#:~:text=The first difference is the,125” longer throat.

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In my opinion, you won't get the best accuracy out of any centerfire rifle unless you load your own ammo. In that sense, I don't think it matters. You tune the ammo to the rifle. 90% (a made up number) of that is going to be the barrel. But even a rifle with a good barrel will shoot better with ammo loaded specifically for it.

Here are some 100 yard groups with a .222 Remington barrel (1:12). The point of the test was to show the effect of different seating depths of the bullet in the case. Differences are measured to the bullet ogive and changes in 1/100ths of an inch.

 

I'm really just looking for an answer as to whether, in-general, shooting .223 in a rifle designed for 5.56 (and .223) will hurt accuracy, without having to put thousands of rounds thru it. It "plinks" with it just fine, and we only have access to a 25yd indoor range other than when we are competing so there's not much to be learned there.

We started shooting a monthly 100yd iron-sight with a 10/22 in August, and now want to try this silhouette match in March (my daughter ships out in April). The MMR is what it is, I've read a bunch of reviews/ratings and in-general, I think we're in good shape for getting started. I already have a trigger upgrade in mind, as I know what a difference that can make.

I simply need to find some quality ammo and am wondering whether I should eliminate .223 from my search (as I'm finding more of that available than 5.56.)

 

A 556 chamber is larger than 223, and subsequently so is the throat, to accommodate for dirty ammo in battle conditions. You can fire 223 ammo in a 556 chambered rifle, where the reverse is not true, nor safe; so you are good there.

Shooting 223 cased ammo in 556 chambered barrels will cause the cases to enlarge much then in 223 chambered barrels. If you reload you to have to work the cases significantly back down to 223, shortening case life.

To get the highest accuracy potential out of a 556 chambered rifle, or realistically any rifle, you will want to hand load ammo setting overall length of the projectile in the case for no more than 3,000ths off the lands. This is what we do for long-range shooting, 600 yd and beyond, and these rounds will not fit in a standard magazine, the overall length is too long. Long range ammo is usually single round loaded into the chamber.

The short answer to your question is using match Grade 223 ammo in a rifle chambered for 556 will not be as accurate as in a rifle chambered for 223. Most of the accuracy burden, in my experience, is going to lie in the hands of the shooter, more so than the equipment.

Sorry for the long response.

Why don't you try several different kinds of ammo in your rifle and see what shoots, groups best at the distance you plan on shooting.

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I can come up with the logic that tells a story, but my experience tells me the answer lies in the land of “it depends”. I never noticed a difference between any 223 and 556 ammo. But I did find ONE BOX ammo that shot lights out for an AR. 15 shots in 7/16” group at 100 yds . It was a one time cherry picked event and I was never able to duplicate it again .

Most of them are not precision rifles , but with enough load experimentation and a Tikka chassis rifle (not an AR and can’t remember name.. T3X tac maybe?) I have frequently shot cloverleaf 5 shot groups at 100 yds .

It was a friends rifle . He custom developed the loads. But the rifle was a 1 moa with factory Hornady ammo.

 

I never noticed a difference between any 223 and 556 ammo.

Thank you!

As this is off-hand out to 500 yards, and we are not experienced shooters, MOA-level accuracy is not necessary. As long as "all .223" isn't going to be drastically different, then we should be fine with just using quality rounds.

Now to figure out what qualifies!

 

There is a lot of good and true information posted in this thread and some false statements.

Have you ever seen load data for 5.56 vs .223
NO

Here are some facts.

-The chambers are different and manly in the throat.
Like said above to shoot dirty ammo in the battle field or long bullets like tracer rounds.
- A 5.56 chambered gun that shoots a 5.56 or .223 labeled round will grow to the size of the chamber.
So now if your reloading ammo that was shot from a 5.56 chamber and try to put that new round in a .223 chambered gun.. depending on the real chamber, the casing may be to big or long and be tight. Or hold more powder. Later on case capacity.
The case needs to be trimmed so you don't jam the round or case up into the lands of the .223 chambered gun. This is where pressure problems can occur.
- Re loading,
Sometimes a 5.56 brass has thicker walls and not as much case capacity, volume.
So.. if you have a good recipe with brass brand A and it's near max or hot and you switch brass or reload random brass B and don't check case capacity you can run into pressure signs. Or blow primers etc.. in a .223 chambered gun. Guess what, if your not careful you can do it in a 5.55 chambered gun.
In a 5.56 chambered gun you can run the 80-90gn bullets out like they should be to be close to the lands and keep enough case capacity to push that baby across the field.

So.. in factory ammunition you can shoot either labeled .223 or .556 ammo from your rifle no matter what the rifles chamber is, .223 Wylde or 5.56
Safely

Think of those chambers with factory ammo like
Match, semi match, open chamber.
You wouldn't shoot stingers out of a match chamber and you wouldn't shoot a oversized necked case with long bullets in a .223 chamber

I shoot a savage 10, 21" barrel 1/9 twist with the barrel chambered and head spaced set according to a stock off the shelf mk262 load.
That's a mag length 77gn Sierra match king load. Running hot. 2850fps
That's mil spec 5.56 ammo.
No signs of over pressure

So.. to your point and two your question from my experience
Off the shelf loads no matter labeled 5.56 or .223 will shoot more accurate from a .223 chambered gun.
I suggest fire forming your brass and reload it using the ladder test to see where your accuracy is.

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Sometimes a 5.56 brass has thicker walls and not as much case capacity, volume.
So.. if you have a good recipe with brass brand A and it's near max or hot and you switch brass or reload random brass B and don't check case capacity you can run into pressure signs. Or blow primers etc..

I have a CZ 527, ostensibly chambered in 223 Rem, and several ARs in both 5.56x45 and 223 Rem. I am an inveterate brass scrounger and handloader and have loaded thousands of rounds in this caliber across dozens of headstamps.

I also load for 300 BLK, and I make the cases out of 223 and 5.56 hulls (cases fired in machine guns with split mouths are great raw materials for 300 BLK cases). Here is what I have found: In general there is very little difference in case wall thickness in domestically manufactured cases in the USA for either chamber designation. Foreign manufactured cases with NATO headstamps and many foreign commercial headstamps tend to have thicker case walls. This characteristic is well known among 300 BLK handloaders who prefer to make their own cases from either 223 or 5.56. So, Kilerham brings up an important point. If you are handloading and keeping with US-manufactured cases, you most likely don't need to be concerned. However, if you are using Wolf, GECO, S&B, or other imported brass, you should probably back off the charge a little and work your way up.

 

View attachment 223-556 chambers.pdf

Chamber reamer specifications for .223 and 5.56 bolt guns and AR/M16s are all over the place, as the table shows. And that's just a partial listing. The one consistent difference is in the throat/leade section, as Hornady correctly states. A longer throat does not stretch brass. Also note some .223 chambers are larger than 5.56 chambers in certain dimensions.

Does it matter? Not one empty case fired from any of my M16 uppers has stretched enough to a) result in an incipient separation or b) require small base sizing. I've obtained and used brass fired from many other ARs and M16s. Same, ie., no pieces evidencing enough stretch to bother.

The grain of truth re sloppy 5.56 chambers involves Minimis:

View attachment headspace.pdf

Been down that road, too, with resulting complete separations. What did I learn?
The best approach to badly stretched brass from minimis is to cull. Nowadays if I get some brass derived from a minimi I plunk it in the Wilson case gauge before sizing. If it's badly stretched, cull it right there so not to worry about a separation at some point.

Most folks never encounter brass fired from Minimis, tho.

 

Since you are running an AR 15 clone you should find out what the barrel
twist is then match the 5.56 ammo bullet weight too your rifle.

Me I have a .223 Rem 700 BDL HB Varmint with a 1-12 twist barrel and is a 50 -60 gr bullet rifle, have
shot 5.56 55gr FMJ for plinking ammo with no problems...but its' it a bolt action and a lot more forgiving.
If it was my rifle and it's a AR 15 semi-auto I would shoot only 5.56 ammo
I have witnessed at the range AR-15 clone rifles with shell cases ripped in 1/2 when the rifle ejected
the empty case and there rifle was out of commission for that range visit...lol.
So yah I would stick with 5.56 ammo and should have the proper powder load to operate AR 15 semi auto rifles vrs
. 223 ammo

I also take that you don't reload.

 

Well, all of this is moot..

Just realized under 6mm bore not permitted, so I'll be using my 308 - which, other than trying to find ammo, works out well, as it has a really nice (and adjustable) trigger..

 

And all even before someone could get some popcorn.

5.56 vs .223 can get heated. But I'm sure you noticed the direction.

The .308 will sure make your shoulder aware much quicker. But have fun.