Confusion over the whole 223 vs. 5.56 thing…

[2ndAmendmentNut]

First off please verify whether or not I understand the differences between the 223 and 5.56 NATO correctly.

The 223 has thinner brass, slightly more case capacity, a shorter neck, loaded in the 50,000 cup range, generally loaded with 55gr or lighter bullets, barrels stamped “223” typically have a slower twist 1-12 rifling.

The 5.56 NATO has thicker brass, slightly less case capacity, a crimped in primer with a hard cup, a longer neck, loaded to higher 60,000 cup, generally loaded with 62+gr or heaver bullets, and barrels stamped “5.56” typically sport a faster twist 1-9 (or faster) rifling in order to stabilize the longer heaver bullets. Do I have that right?

When it comes to shooting “factory” ammo there is not that much to worry about, only the shooter should watch for signs of pressure and understand that their rifle will shoot best with the ammo marked the same as their barrel. Is this for the most part true?

The only real thing to worry about is the fact that 5.56 brass has less case capacity so using 223 load data could prove to be potentially dangerous. Of course a prudent handloader understands the importance of working up slowly, so this is an unlikely situation. Did I get that correct?

My next question is what sort of reloading dies do I need to load 5.56 ammo? Will 223 dies work seeing as external dimensions are virtually the same save for the longer neck, or do I need dies marked “5.56” for best results?

[tomme boy]

Dies are the same. Just because it is 5.56 brass does not mean it has less capacity. I do not think you will ever find actual 5.56 data. So load with any of the 223 data and you will be fine.

[montana_charlie]

Actually, the designations .223 Remington and 5.56 NATO are indicative of the chamber of the rifle.
Ammunition companies then make ammo that is safe to fire in one chamber, or the other, or both.

The chamber differences are slight, but measurable. The NATO chamber has a slightly longer throat.
Military ammunition is loaded to high pressure and expects to be fired in a chamber with a longer throat. Imagine the potential for a pressure spike if that (military) ammo is used in a tight-throated .223 Remington chamber ...

When the M16 was first issued, the barrel had a 1 in 12 twist, and the ammunition used the 55 grain bullet. 1 in 12 is a slow twist, but it stabilized the bullet to the degree called for by the requirements of the day.
But, it was 'American ammunition' and other NATO countries had their own weapons with matching ammuntion. The M193 55gr. M16 round was not a 'NATO' round because it was only used by us.
(During those days, the only NATO round we used was the .30 caliber 7.62mm NATO)

When NATO did adopt a 5.56x45 round for general issue, they did not like the M193 because the wounds it caused were considered inhumane.
Instead, the 62 grain SS109 bullet fron Belgium was adopted in ammuntion designated M855 NATO.

Because the bullet is so long, the old 1 in 12 twist (in American rifles) was unsuitable, so Colt's testing came up with the current 1 in 7 twist. It will stabilize the SS109 bullet, but isn't much good with the old M193 loading.

There are a number of rifling twists available to choose from, and 1 in 7 is a good choice if you plan to shoot bullets of 60 grains or more.
But, if you are looking for flexibility to shoot a variety, the 1 in 9 twist fills the bill quite well.
If you have a 1 in 12 barrel, you are limited to the short bullet or short range, for all practical purposes.

Because a 5.56 NATO chamber will handle military ammunition, it will easily take .223 Remington ammo. The opposite is a bit dicey, especially when M855 ammo is used.

If loading your own you could seat the bullet deeper to better fit the throat in a .223 Rem chamber, but you run the risk of increasing the pressure generated by decreasing case volume.

I don't reload AR ammo, so I won't say anything about the best dies to use.

Did I leave anything out?

CM

[badgeredd]

To my understanding, you nailed it MC.
223 IS safe in 5.56 guns, but the opposite could be dangerous.
I once had a gun shop owner tell me (he was wrong) that 223 couldn't be used in a 5,56 firearm. Needless to say, I view all comments by said shop owner to be suspect.

Edd

[M-Tecs]

Montana Charlie’s info is 100%. The difference that the NATO chamber has a slightly longer throat.

Your statement that the 223 has thinner brass, slightly more case capacity, a shorter neck and the 5.56 NATO has thicker brass, slightly less case capacity, a longer neck is not correct.

Most 5.56 does have crimped primer pockets but not all. The frangible training ammo does not have crimped primer pockets. The necks lengths are the same between the 223 and 5.56 NATO

Case volume is the same or slightly greater for the 5.56. I have compared numerous years of LC & WCC GI brass to Winchester, Remington, PMC and Federal. It's basically the same with Federal having the least volume.

In the 308 and 3006 I have found that the military brass does have less case volume. I have never found a difference with the .556.

More info here http://www.6mmbr.com/223Rem.html

.223 Rem Case Weight vs. Capacity
Case Manufacturer Case Weight* H20 Capacity**
Lake City 06 92.0 30.6
WCC99 95.5 30.5
Sellier & Belloit 92.3 30.5
Remington 92.3 30.4
PMC 93.5 30.4
Hirtenberger 93.7 30.4
Lake City 04 93.0 30.4
Federal 96.3 30.2
Hornady 93.9 30.1
IMG (Guatemalan) 95.4 30.1
Lapua (new lot) 93.4 30.1
Winchester 93.9 30.1
Olympic 97.4 30.0
Radway Arsenal 96.1 30.0
PMP 104.5 29.9
FNM 93-1 97.3 29.8
Lapua (old lot) 104.0 28.0

[excess650]

1-12" twist is considerably quicker than the 1-16" used in the Hornet and Bee and 1-14" used for 222, 222 Magnum, 22-250, 225 Winchester, 224 Weatherby, and 220 Swift.

I had a 700VS in 223 with 1-12" twist and it shot 60gr Hornady and 63gr Sierras rather accurately. Ruger used a 1-10" twist in the #3 carbine 223, and it handled the 70gr Speer just fine. The quicker than 1-12" twist caused Hornady SX and Hornet bullets to be quite frangible.

The 1-9" is probably the best compromise for a gas gun, IMO. The 1-7" will shoot 55gr just fine, but may take a bit of load development.

[Larry Gibson]

First off please verify whether or not I understand the differences between the 223 and 5.56 NATO correctly.

The 223 has thinner brass, slightly more case capacity, a shorter neck, loaded in the 50,000 cup range, generally loaded with 55gr or lighter bullets, barrels stamped “223” typically have a slower twist 1-12 rifling.

Nothing correct. Some .223 cases have thicker brass than some lots of 5.56 cases, essentially it varies. The case dimensions are the same including the case necks. As with 7.62 NATO vs the .308W some commercial .223 is loaded "hotter" than some 5.56 NATO and visa versa. Yes, I measure pressures, not guestimate, and have measured the differences. Commercial .223 is loaded with 40 - 75 (perhaps 80 gr) gr bullets. Milsurp 5.56 is loaded with 55 - 75 gr bullets. Barrels stamped ".223" can have 7, 8 9, 10, 12 and 14" twists. The only difference between the two is the chamber throats are longer and the dimensions are a tudge larger in the 5.56.

The 5.56 NATO has thicker brass, slightly less case capacity, a crimped in primer with a hard cup, a longer neck, loaded to higher 60,000 cup, generally loaded with 62+gr or heaver bullets, and barrels stamped “5.56” typically sport a faster twist 1-9 (or faster) rifling in order to stabilize the longer heaver bullets. Do I have that right?

Only thing correct there is the milsurp cases have crimped in primers. Everything else is wrong.

When it comes to shooting “factory” ammo there is not that much to worry about, only the shooter should watch for signs of pressure and understand that their rifle will shoot best with the ammo marked the same as their barrel. Is this for the most part true?

Shooting the heavier bullet (64+ gr) and higher milsurp in the tighter chambered and shorter throated .223 commercial chambers can give excessive pressures.

The only real thing to worry about is the fact that 5.56 brass has less case capacity so using 223 load data could prove to be potentially dangerous. Of course a prudent handloader understands the importance of working up slowly, so this is an unlikely situation. Did I get that correct?

No, you did not get that correct. The case capacity varies with the lot and manufacture. Some .223 has a smaller capacity than some milsurp.

My next question is what sort of reloading dies do I need to load 5.56 ammo? Will 223 dies work seeing as external dimensions are virtually the same save for the longer neck, or do I need dies marked “5.56” for best results?

You need to get .223 dies. Just as with the 7.62 NATO there are no real 5.56 NATO dies. I suggest you get the regular RCBS X-dies. The SB'd dies are not needed. With the X-die properly adjusted you will get 2 - 3 times the case life and will not have to trim.

Larry Gibson

[gew98]

1-12" twist is considerably quicker than the 1-16" used in the Hornet and Bee and 1-14" used for 222, 222 Magnum, 22-250, 225 Winchester, 224 Weatherby, and 220 Swift.

I had a 700VS in 223 with 1-12" twist and it shot 60gr Hornady and 63gr Sierras rather accurately. Ruger used a 1-10" twist in the #3 carbine 223, and it handled the 70gr Speer just fine. The quicker than 1-12" twist caused Hornady SX and Hornet bullets to be quite frangible.

The 1-9" is probably the best compromise for a gas gun, IMO. The 1-7" will shoot 55gr just fine, but may take a bit of load development.

The first AR's issued for trials by the US gov't had 1-14 twist. And a significantly more pointed 55 gn bullet profile. These were the first rifles sent to vietnam during the Kennedy Admin ...which proved the very lethal nature of small caliber high velocity projectiles on flesh. But in further testing in "arctic" conditions it was found the 1-14 twist failed to adequately stabilize the 55gn bullet in severe cold weather , hence the production change on further issue rifles to 1-12.
And as the rifle became the issue rifle the ammunition manufacturers took it upon themselves to change the bullet profile to make it more economical to produce which played a part in less effective wounding/killing properties.
It is my understaning that NATO had not a problem with the 55 gn pills' lethality , but it's lack of range and cover penetration. Hence the slower , heavier and less lethal SS109 came about . I have experianced some 1-9 twist AR's that handle 55 grainers well and some that act like 1-7 with M193 ball.
I used to win bets on the range by taking M16A2's and putting one M193 then two M855 .. and the last round on burst almost always keyholed or was so far off to be about useless. The M16A1 did nealry identically poor with M855 ball with a pronounced amount of bullet fouling.
Having a couple friends back from A'stan recently and some that were in Iraq years ago there was little love by any of them for M855 ball...it simply did not live up to the task whereas the M193 certainly did when it connected with the "target".

[MtGun44]

I don't think the necks, or any other case dimensions are different.

I think it is only the chamber dimensions (IIRC it is mostly throats) and pressure limits
(SAAMI vs US military) that are different, as far as any standards. Ammo is all over
the map.

Bill

[2ndAmendmentNut]

Okay so I was wrong, I can admit, and accept. Thanks for clearing that up for me.

[Larry Gibson]

Okay so I was wrong, I can admit, and accept. Thanks for clearing that up for me.

No problem with being wrong about a lot of this. Much of what you've said is repeated so often in books, articles and in the internet that it soon becomes the "truth/fact". All is a fine example that "concensous" of opinion does make it fact. We live, we make mistakes and we learn, hopefully

Larry Gibson

[ilcop22]

Gun with barrel marked 5.56 = Shoots either .223 or .556.
Gun with barrel marked .223 = ONLY shoots .223.

1-7 twist rate = Shoots heavier bullets better.
1-9 twist rate = Great with lighter bullets.

That's pretty much the simplest way to explain it.

[gew98]

Gun with barrel marked 5.56 = Shoots either .223 or .556.
Gun with barrel marked .223 = ONLY shoots .223.

1-7 twist rate = Shoots heavier bullets better.
1-9 twist rate = Great with lighter bullets.

That's pretty much the simplest way to explain it.

1-7 twist is for 62 grainers

1-9 twist is the "compromise twist" so one can allegedly shoot 55 grainers and 62's in their AR's. Truth is some 1-9 barrels won't do 55 grainers and some will. I wish someone would come out with M4orgery profile barrels ( 16" ) with 1-12 twist. I have seen the 1-12 XM177 barrels going for $240 + and that's just crazy for an under 16" tube you would have to have the FH pinned on.

[c3d4b2]

Here is some info to further confuse the issue..

http://njhighpower.com/cart_tech.htm

[ilcop22]

1-7 twist is for 62 grainers

1-9 twist is the "compromise twist" so one can allegedly shoot 55 grainers and 62's in their AR's. Truth is some 1-9 barrels won't do 55 grainers and some will. I wish someone would come out with M4orgery profile barrels ( 16" ) with 1-12 twist. I have seen the 1-12 XM177 barrels going for $240 + and that's just crazy for an under 16" tube you would have to have the FH pinned on.

Well, the you also have the 1-8" twist barrels...

I know some manufacturers who make 1-12" twise barrels, but the shortest I've seen is an 18" varmint barrel.

Personally, I like the 1-7" twist rate barrels, since they have the widest range of bullet weights they can accurately handle .

[zxcvbob]

I'm new to this platform (Ruger 581 Mini-14.) With a 16" barrel and a 1:9 twist, should I be using 55 grain bullets or 62's? I know both will work, but which will be easier to find an accurate load?

BTW, the Rugers are marked ".223" but the owners manual says all except the target models can handle any .223 or 5.56 ammo. (since they cut a 5.56 chamber, why didn't they stamp that on the receiver? )

[MtGun44]

Maybe because some countries do not permit guns that are chambered in a "military
cartridge" for civilians. MAYBE - a .223 is not a military cartridge, but seems a bit far
fetched.

As to which will shoot better - in depends on a lot of stuff and the only way to really find
out is to try them.

Bill

[ilcop22]

I'm new to this platform (Ruger 581 Mini-14.) With a 16" barrel and a 1:9 twist, should I be using 55 grain bullets or 62's? I know both will work, but which will be easier to find an accurate load?

BTW, the Rugers are marked ".223" but the owners manual says all except the target models can handle any .223 or 5.56 ammo. (since they cut a 5.56 chamber, why didn't they stamp that on the receiver? )

Well, they typically stamp the chambering on the barrel itself, not the receiver. That would be why it's not stamped on the receiver. If the manual says any .223 or 5.56 ammo, then it would stand to reason that the chamber is cut to handle either round.

As for which bullet is better, you'll need to shoot them to find out. My AR has a 16" 1-9" match barrel, and the most accurate round in that rifle is a 53 grain match H.P bullet on top of 26-27 grains of Varget.

[GabbyM]

You can easily look up the chamber drawings for 223 and 5.56.
5.56 chambers have the longer free bore and are larger by one thousandths or more in a few spots. Loaded rounds are the same dimension inside and out. Variations only occur from brand to brand as to brass thickness. Pressure limits are very high for 5.56 NATO and they have been risen for the new ammo our Army issues. That should not be an issue as we will never be able to purchase that ammo and we have no need for it.
However it’s pressure is over 60M PSI from a NATO free bored chamber. May or may not see more pressure from a 223 SAMI chamber. I’ve two 223 SAMI rifles and one 5.56mm NATO chambered AR with 12 twist barrel. Velocities are similar in all three. In fact my old SP-1 with 12 twist 20” barrel NATO chamber turns in higher velocity than a book would predict compared to my 9” twist 223 Rem chambered AR with 20” barrel or my 26” barrel varmint rig. So I can’t see where the long throat and fatter chamber is giving up anything to the tight chambered guns. Accuracy is better with the SAMI chambers but that may only be because those are both heavy barrel guns that will drill a single hole at 100 yards while the 6 ½ pound noodle barrel SP-1 only shoots 1 1/8” groups all day long with a 3X Colt scope and match bullets over some 4198 powder. Oh and sorted brass with uniformed flash holes an primer pockets and all that stuff. Same ammo that gives one hole groups in the heavy rifles.

One thing I know for sure. I’d never elect to carry my heavy AR with 223 SAMI chamber into a war. No more than you give up with that little bit of slop in a NATO chamber for the huge jump in reliability of the system in harsh environments. Actually moderate environments will stick a SAMI chambered AR.

In reference to previous post. 5.56NATO dies are out there. I’ve a NATO sizer die from RCBS. It’s an old 223 Rem die that has minimal sized thousands of cases from 5.56mm chambers. At this point in this dies life you can turn it al the way down on the shell holder and it still will not size a fat case to fit a new tight chamber in 223 REM. If you do not want to wait for ten thousand rounds to lap out your 223 die. Try a piece of 20 pound paper with a nominal thickness of .003” between the die and shell holder. You’ll probably need to screw your die in a tad more as the NATO chamber isn’t all that much larger

[1Shirt]

Just returned from a P-Dog shoot in Co. Shot mostly 223 in a Sav w/1-9 twist, and 40 gr. blts. at about 3600. Longest kill was just under 400 yd. Avg distance of kills was about 250.
1Shirt!