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.223 Remington vs. 5.56 NATO: What You Donít Know Could Hurt You
Human Events ^ | 02/15/2011 | Richard Johnson

Posted on 02/21/2011 7:37:41 PM PST by neverdem

Is firing a 5.56 NATO cartridge in your .223 Remington chambered AR15 dangerous? Or do Internet forum-ninjas and ammunition companies selling you commercial ammo instead of surplus overstate the dangers? Believe it or not, a real danger exists, and some gun owners who think they are doing the right thing may not be safe.

The Cartridges

The .223 Remington and 5.56x45 NATO cartridges are very similar, and externally appear the same. But there are some differences that lie beneath the surface.

The 5.56 case has thicker walls to handle higher pressures, meaning the interior volume of the case is smaller than that of a .223. This will alter the loading data used when reloading 5.56 brass to .223 specs.

Some 5.56 loads have a slightly longer overall length than commercial .223 loads.

The Chambers

The significant difference between the .223 Rem and 5.56 NATO lies in the rifles, rather than the cartridges themselves. Both the .223 and 5.56 rounds will chamber in rifles designed for either cartridge, but the critical component, leade, will be different in each rifle.

The leade is the area of the barrel in front of the chamber prior to where the rifling begins. This is where the loaded bullet is located when a cartridge is chambered. The leade is frequently called the “throat.”

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.

The reverse situation, a .223 Rem round in a 5.56 NATO gun, isn’t dangerous. The leade is longer, so a slight loss in velocity and accuracy may be experienced, but there is not a danger of increased pressures and subsequent catastrophic failure.

How serious is the danger of firing 5.56 ammo in .223 guns? Dangerous enough that the SAAMI lists 5.56 military ammo as being not for use in .223 firearms in the technical data sheet titled “Unsafe Firearm-Ammunition Combinations.”

ATK, the parent company of ammunition manufacturers Federal Cartridge Company and Speer, published a bulletin entitled “The Difference Between 223 Rem and 5.56 Military Cartridges.” In this bulletin, ATK stated using 5.56 ammo in a .223 rifle could result in “…primer pocket gas leaks, blown cartridge case heads, and gun functioning issues.”

However, the danger may be lower than SAAMI or ATK suggest. In Technical Note #74 from ArmaLite, the company states “millions of rounds of NATO ammunition have been fired safely in Eagle Arms and ArmaLite’s® SAAMI chambers over the past 22 years,” and they have not had any catastrophic failures.

According to ArmaLite:

“Occasionally a non-standard round (of generally imported) ammunition will fit too tightly in the leade, and resistance to early bullet movement can cause elevated chamber pressures. These pressures are revealed by overly flattened primers or by powder stains around the primer that reveal leaking gasses.”

What Do You Have?

So, if you own a rifle chambered for the .223 for 5.56, do you know for which caliber it is really chambered?

Many match rifles are chambered in .223 Remington (SAAMI specs) for tighter tolerances, and theoretically better accuracy.

Many of the AR-15’s currently sold on the market are made for the 5.56 NATO cartridge. If you own one of these, you should be fine with any .223 or 5.56 ammunition.

However, ATK dropped this bomb in the bulletin on the .223/5.56:

“It is our understanding that commercially available AR15’s and M16’s – although some are stamped 5.56 Rem on the receiver – are manufactured with .223 chambers.”

So, even if your AR is stamped 5.56, is it really? Check your owner’s manual or call the company directly and make sure you get an answer you feel comfortable with.

As if the confusion regarding the .223 vs 5.56 chambers wasn’t enough, there is a third possibility in the mix, that is being used by at least one major manufacturer. The .223 Wylde chamber is a modified SAAMI-spec .223 chamber that allows for the safe use of 5.56 NATO rounds, but maintains tighter tolerances for better accuracy.

Yeah, yeah… What’s the bottom line?

Here’s the bottom line. If you want to follow the safest possible course, always shoot .223 Remington ammunition. The .223 Rem cartridge will safely shoot in any rifle chambered for the .223 or 5.56.

If you want to shoot 5.56 NATO rounds, make sure you have a rifle designed for the 5.56 military cartridge. Shooting 5.56 in a normal .223 Rem rifle can result in bad things.


TOPICS: Constitution/Conservatism; Culture/Society; Extended News; News/Current Events
KEYWORDS: 223remington; 556nato; ar15; arfcom; banglist
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1 posted on 02/21/2011 7:37:49 PM PST by neverdem
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To: neverdem

OR, you could do your own forensics and determine the actual specs on your weapon!


2 posted on 02/21/2011 7:41:20 PM PST by G Larry
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To: neverdem

So how does impact a Ruger Mini14? The military stuff is cheaper. Best not use it in that rifle?


3 posted on 02/21/2011 7:42:12 PM PST by ReverendJames (Only A Painter Or A Liberal Can Change Black To White.)
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To: neverdem
Get an AK variant chambered for 7.62 x 39.

Problem solved.

4 posted on 02/21/2011 7:44:14 PM PST by SIDENET ("If that's your best, your best won't do." -Dee Snider)
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To: neverdem

Yes if its marked .223 it is dangerous. If its a bolt action marked .223 a 5.56 is totallly dangerous and overpowered. An M-4 which is a 5.56 but will take a .223 is a different situation.


5 posted on 02/21/2011 7:47:13 PM PST by Georgia Girl 2 (The only purpose of a pistol is to fight your way back to the rifle you should never have dropped.)
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To: ReverendJames
So how does impact a Ruger Mini14? The military stuff is cheaper. Best not use it in that rifle?

No worries. You can safely fire the 5.56 round in the mini 14.

(Google Ruger_Mini-14)

.

6 posted on 02/21/2011 7:49:57 PM PST by Seaplaner (Never give in. Never give in. Never...except to convictions of honour and good sense. W. Churchill)
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To: Seaplaner

Thanks.


7 posted on 02/21/2011 7:50:59 PM PST by ReverendJames (Only A Painter Or A Liberal Can Change Black To White.)
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To: neverdem
This is surprising; I have always seen them presented as interchangeable. This is a great site that lists them together ...
8 posted on 02/21/2011 7:54:46 PM PST by hemogoblin
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To: ReverendJames

As I recall Ruger’s manual, the warrantee is voided if you fire military 5.56 ammo in the Mini-14.


9 posted on 02/21/2011 7:56:45 PM PST by 'smith
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To: neverdem
Both my AR uppers are 5.56. The Rem .223 ammo is not as accurate out of them as the NATO stuff. No surprise there. I chose 5.56 because I can safely shoot the .223. I reload the NATO brass for varmint hunting and knocking the paint off the gongs at 300 meters.
10 posted on 02/21/2011 8:00:37 PM PST by 50cal Smokepole (Effective gun control involves effective recoil management)
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To: neverdem

If you reload , load to max. OAL. This will lower pressures significantly.


11 posted on 02/21/2011 8:01:00 PM PST by rsobin
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To: neverdem

Hmmmm...


12 posted on 02/21/2011 8:02:04 PM PST by SuperLuminal (Where is another agitator for republicanism like Sam Adams when we need him?)
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To: Clint N. Suhks; mylife; davetex

EBR Ping!


13 posted on 02/21/2011 8:04:00 PM PST by 50cal Smokepole (Effective gun control involves effective recoil management)
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To: neverdem
.308 there's no substitute...
14 posted on 02/21/2011 8:04:11 PM PST by Chode (American Hedonist - *DTOM* -ww- NO Pity for the LAZY)
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To: ReverendJames

a Friend asked me that last week, I sent him this article.

Ruger makes the mini in a 5.56.

He has a mini-14 .223, saw a deal on one in 5.56, told him he could buy it, but he could only stock .223 in his stash, so as not to mix up the ammo.

I told him to either sell the .223 and get 2 5.56, or just look for another .223


15 posted on 02/21/2011 8:05:28 PM PST by JMJJR ( Newspeak is the official language of Oceania)
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To: ReverendJames
We have a colt preban A2, couple staggs, 3 mini-14s; have shot both; never any problems.

Since I got the 6.8 spc, never shoot the original AR's much. I'm picking up a 338 fed AR-10 armalite soon as our road opens too. Luv all the new calibers for the AR platform.

16 posted on 02/21/2011 8:06:11 PM PST by Eska
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To: neverdem
I have 2 AR-15s and never fired anything other than surplus ammo.

I have never had a problem in either rifle.

17 posted on 02/21/2011 8:10:48 PM PST by Pontiac
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To: 50cal Smokepole

I’m sure Smith & Wesson M&P15 is a real 5.56mm NATO or else there’d be some big law suits. What does your Stag say it is?

This pretty much proves your theory 5.56 is better than .223 given those specs.


18 posted on 02/21/2011 8:16:10 PM PST by Clint N. Suhks (YOU BETCHA!)
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To: ReverendJames
So how does impact a Ruger Mini14? The military stuff is cheaper. Best not use it in that rifle?

Reading the Fine Manual, it says:

"RUGER® MINI-14® RANCH RIFLES are offered in two calibers: .223 Rem. (5.56mm) and 6.8mm Rem. SPC. The Target Model Mini-14 is chambered for .223 Remington ammunition only."
So, if you have the Ranch model, you can shoot 5.56. If you have the Target model, you should not shoot 5.56.
19 posted on 02/21/2011 8:16:33 PM PST by Yo-Yo (Is the /sarc tag really necessary?)
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To: ReverendJames

According to my friend, his circa late 90’s Series 196 Ranch Rifle owner’s manual states it can digest either. Specifically, “The Ranch Rifle is designed to use either standariz(sic) U.S. military or factory loaded sporting .223 (5.56mm) cartridges manufactured in accordance with U.S. industry practice.”

Don’t know about the other series. YMMV, of course.


20 posted on 02/21/2011 8:17:43 PM PST by Strzelec
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To: Chode
" .308 there's no substitute..."

Believe it or not, a reverse condition exists with the beloved .308.

By reverse, I mean an increased failure risk in some rifles to use civilian .308 in a NATO spec 7.62X51mm chamber. Some of the hundred plus year old pre 1898 mausers converted to 7.62X51mm come to mind.

21 posted on 02/21/2011 8:21:41 PM PST by labette ( Humble student of Thinkology)
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To: neverdem
Q. Can you shoot 5.56 mm ammo in Ruger Mini 14?

A. Yes you can, the Mini 14 has always had a 5.56x45 chamber.

The mini14 receiver is marked ".223 CAL" not ".223 rem."

22 posted on 02/21/2011 8:23:46 PM PST by E. Pluribus Unum ("If they bring a knife to the fight, we bring a gun." -- Barry Soetoro, June 11, 2008)
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To: ReverendJames

If you reload your own ammo and are careful to keep the charges out of the max muzzle velocity range and keep the overall length of the finished cartridge at the .223 Remington spec., using once fired 5.56 brass should not pose a problem.
What the article tells us is that using FACTORY loaded NATO 5.56 in a weapon — like the Mini-14 — chambered for .223 can cause a problem.


23 posted on 02/21/2011 8:25:42 PM PST by Dick Bachert
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To: neverdem

sfl


24 posted on 02/21/2011 8:30:26 PM PST by phockthis
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To: labette; Chode

OT

Met an Army Sniper in between tours who sold me a Glock working at the local gun shop this weekend. He said they use .308 bolt and M-16 exclusively unless they need to shoot through a car or cinder block then they use 50mm. I asked why they don’t use a .300 win mag and he said the Army is converting over to them soon. FWIW


25 posted on 02/21/2011 8:32:30 PM PST by Clint N. Suhks (YOU BETCHA!)
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To: Seaplaner
No worries. You can safely fire the 5.56 round in the mini 14.

You're correct. The manual that came with my mini-14 clearly spelled that out.

26 posted on 02/21/2011 8:32:30 PM PST by ExtremeUnction
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To: All
Tons of info for all AR-15 owners:

AR-15

27 posted on 02/21/2011 8:34:47 PM PST by BushMeister ("We are a nation that has a government - not the other way around." --Ronald Reagan)
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To: labette
yeah, could mean trouble...
28 posted on 02/21/2011 8:35:30 PM PST by Chode (American Hedonist - *DTOM* -ww- NO Pity for the LAZY)
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To: Clint N. Suhks
The Stag is 5.56. The custom varmint upper is also 5.56. The “leade” mentioned in the article is the key. The fine folks over at Sinclair International stressed that I pay attention to COAL (cartridge overall length). The Barnes Varmint Grenades I use like a little space before the rifling.
29 posted on 02/21/2011 8:41:04 PM PST by 50cal Smokepole (Effective gun control involves effective recoil management)
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To: neverdem
I did my homework on this before I bought my AR15 in 5.56.

To the novice, the two rounds look identical.


30 posted on 02/21/2011 8:46:07 PM PST by Cobra64
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To: 50cal Smokepole
I chose 5.56 because I can safely shoot the .223.

Me too.

31 posted on 02/21/2011 8:47:35 PM PST by Cobra64
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To: Clint N. Suhks
He said they use .308 bolt and M-16 exclusively unless they need to shoot through a car or cinder block then they use 50mm

50 MM, Holy super bore Batman,That'll knock your fillings loose. ;-)

32 posted on 02/21/2011 8:52:29 PM PST by HP8753 (Live Free!!!! .............or don't.)
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To: neverdem

LOL, when you start worrying about the thickness of the copper/brass you have a problem but it has nothing to do with the firearm. LOL


33 posted on 02/21/2011 8:52:29 PM PST by org.whodat
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To: Clint N. Suhks
damn, i'd thought they'd go for the .338
34 posted on 02/21/2011 8:53:06 PM PST by Chode (American Hedonist - *DTOM* -ww- NO Pity for the LAZY)
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To: labette

I would not worry much about the Mauser 98’s. Now the Spanish Mauser 95’s are another issue. Some were converted to a homegrown round dimensionally identical to the 7.62x51. With only two locking lugs and the inferior Spanish steel, there is a very serious problem.


35 posted on 02/21/2011 8:56:16 PM PST by JayVee (Joseph)
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To: HP8753

Surprising, not really, they use the 50 very seldomly, so he said, because it weighs 28 pounds.


36 posted on 02/21/2011 9:02:09 PM PST by Clint N. Suhks (YOU BETCHA!)
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To: musicman

BFLR


37 posted on 02/21/2011 9:04:37 PM PST by musicman (Until I see the REAL Long Form Vault BC, he's just "PRES__ENT" Obama = Without "ID")
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To: Clint N. Suhks
I'm assuming you meant the 50 cal BMG. A 50 MM would have close to a 2" bore and would most likely tear the shoulder off anyone trying to shoulder fire such a gun.

The Bradley Fighting vehicle has a 25 mm gun.

I was just poking fun at your typo.

38 posted on 02/21/2011 9:05:41 PM PST by HP8753 (Live Free!!!! .............or don't.)
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To: Chode

When he said .300 win mag, I thought he’d say the Weatherby .300 mag which IIRC has a higher velocity and less drop according to my recipe book.

Not familiar with the .338 though...


39 posted on 02/21/2011 9:07:29 PM PST by Clint N. Suhks (YOU BETCHA!)
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To: HP8753

LOL!

Yeah, metric vs imperial conversions weren’t taught very well at my Publik Skrool...


40 posted on 02/21/2011 9:11:27 PM PST by Clint N. Suhks (YOU BETCHA!)
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To: Cobra64
I tried reloading some .223 brass (after firing from the 5.56 chamber) but it didn't group as well the NATO brass. Still, having the option is much better than not having it. I'll gladly use .223 to take out zombies at 50 yards, where the accuracy difference doesn’t amount to much.
41 posted on 02/21/2011 9:30:03 PM PST by 50cal Smokepole (Effective gun control involves effective recoil management)
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To: SIDENET

Even better:
Mosin-Nagant -> 7.62x54R caliber.


42 posted on 02/21/2011 9:30:51 PM PST by OneWingedShark (Q: Why am I here? A: To do Justly, to love mercy, and to walk humbly with my God.)
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To: Chode

My Remington bolt action “Police Special” has a
.308 chamber with a tight throat. You can’t
safely shoot a 7.62x51 NATO in it. There are
headspacing issues between the two specs.


43 posted on 02/21/2011 9:33:56 PM PST by Myrddin
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To: neverdem
For an AR-15 it doesn't matter what the RECEIVER says.

Check the stampings on the BARREL.

Rock River Arms is known for using the Wylde chamber in their varmint rifles.

AR15 Chambers (pdf file)

44 posted on 02/21/2011 9:43:16 PM PST by smokingfrog ( BORN free - taxed to DEATH (and beyond) ...)
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To: 50cal Smokepole

I agree, and was also aware of the accuracy issue. I bought this weapon for a training class in order to be comfortable and capable of “running the gun” should a serious situation arise.


45 posted on 02/21/2011 9:48:32 PM PST by Cobra64
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To: neverdem

Pretty simple, just trim your cases to specification to be sure you have no head space problems and work your loads up before trying to go for maximum velocity and watch for pressure problems before they occur. You can also check for case internal volume by measuring before you reload your cases to look for case wall thickness affects before setting up your specific load. I have found that the commercial Winchester brass loads pretty much the same as their military brass and the same as Lake City brass. Stay away from the Federal brass.


46 posted on 02/21/2011 9:50:36 PM PST by Mat_Helm
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To: OneWingedShark
Even better: Mosin-Nagant -> 7.62x54R caliber.

Oh, yeah. Gotta love those Mosins! I'm down to only 5 of them, because friends keep buying them from me.

I think they're too lazy to clean the cosmo off, so they go for mine. LOL.

47 posted on 02/22/2011 12:55:02 AM PST by SIDENET ("If that's your best, your best won't do." -Dee Snider)
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To: Clint N. Suhks
Lots of foolish stuff posted here, there is no difference in the two rounds military brass is made thicker for shelf life and refurbishing. The two round, military verse civilian, shoot different because of bullet size and bullet crimping. The 223 civilian is more a varmint load. The original ar15’s were chambered in 222 which was a Remington round, rather than buy rights to use the round, the up sized it a hair and changed the neck slope. So a 223 is a fancy 222:, if you get any deformed brass from shooting it will be an over-sized chamber 99% of the time. The military rifle also has a different barrel twist that the civilian, that also will cause a difference in accuracy.
48 posted on 02/22/2011 3:01:55 AM PST by org.whodat
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To: 50cal Smokepole

Thanks for the ping 50!! Good article.


49 posted on 02/22/2011 3:35:53 AM PST by davetex (All my weapons got melted by a meteor!! No Sh*t)
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To: neverdem

bump


50 posted on 02/22/2011 4:35:19 AM PST by stevie_d_64 (I'm jus' sayin')
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