Shooting .223 in a 5.56 rifle


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Angleiron
December 2, 2009, 01:09 PM
I bought my 5.56 because of the versatility of being able to shoot both types of rounds in a pinch, and was wondering if anyone else is shooting .223 in their 5.56 rifle? I know that it is not as accurate as a shooting these rounds out of a designated .223 rifle, but how much of a difference is there? I have the opportunnity to get 1000 rounds of .223 for a real good price, but if it is a big difference then maybe it is not worth it.

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TexasRifleman
December 2, 2009, 01:10 PM
Accuracy wise I've never been able to tell any difference.

I mean, if it's surplus junk 5.56 I'm shooting maybe, but in general I never notice enough difference to worry about for every day shooting.

stacks04
December 2, 2009, 01:17 PM
accuracy should not suffer either.

mongoose33
December 2, 2009, 01:19 PM
I bought mine in 5.56 for the same reason; I don't notice any difficulties.

rcmodel
December 2, 2009, 01:24 PM
There is more variety of accurate .223 loaded by the factories then there is 5.56.

Most of the 5.56 is loaded with FMJ-BT GI style bullets.
And none of them will prove to be as accurate as any of the .223 match or varmint bullet loads.

As for best accuracy?
Your chance of best accuracy in a 5.56 chambered gun is .223 match or varmint ammo.
Followed by, or equaled by 5.56 Match ammo.

5.56 FMJ-BT will be at the very bottom of the accuracy heap in either chamber in any gun.

rc

wishin
December 2, 2009, 01:36 PM
As I understand it, the .223 has a tighter chamber around the neck and is shorter which purportedly allows for a little more accuracy. RRA's Wylde chamber is supposed to "correct" this so .223 and 5.56 are equally as accurate.

Boba Fett
December 2, 2009, 01:41 PM
I bought mine in 5.56 for the same reason; I don't notice any difficulties.
Same.

No issues and accurate enough as far as I can tell. If I want more accurate I'll get a bolt gun and use match ammo.

W.E.G.
December 2, 2009, 04:32 PM
.223 ammo is OK in 5.56 barrel.

5.56 ammo is not OK in .223 barrel.

This was reported in the American Rifleman magazine recently.

.223 chamber is "smaller" than 5.56 chamber.

http://i227.photobucket.com/albums/dd7/rkba2da/rifle%20pics/AR-15/556-223chambercomparison.gif

.223 Remington vs. 5.56: What’s In a Name


By BRYCE M. TOWSLEY field editor
American Rifleman – September 2007


Most gun guys know the history of the .223 Remington and that it - like so many of our popular cartridges - started life in the military. Because the military switched to metric designations sometime in the 1950s, this little .22-cal. cartridge was later called the 5.56x45 mm NATO (commonly referred to as "5.56x45 mm").

The 5.56x45 mm surfaced in 1957 as an experimental cartridge in the AR-15 rifle. The concept was to develop a smaller, lighter military cartridge that would still be traveling faster than the speed of sound at 500 yds., and this was accomplished by using a 55-gr. boattail bullet. The AR-15 evolved into the select-fire M16 rifle that was adopted by the military in 1964.

Even though it would ultimately kill off its own .222 Rem. and .222 Rem. Mag. cartridges, Remington was quick to act, and very shortly after the military adopted the 5.56x45 mm cartridge the firm brought out the civilian version, called the .223 Remington. Confusion followed.

The common misconception is that the two are the same; that 5.56x45 and .223 Rem. are the same dance partner, but with a different dress. This can lead to a dangerous situation. The outside case dimensions are the same, but there are enough other differences that the two are not completely interchangeable.


One big difference is pressure. It becomes a bit confusing, as the pressure for the two is not measured in the same way. The .223 Rem. is measured with either Copper Units of Pressure (c.u.p.) or -- more recently -- with a mid-case transducer in pounds-per-square-inch (p.s.i.). The military 5.56x45 mm cartridge is measured with a case mouth transducer. The different measuring methods prevent a direct comparison, as a case mouth transducer gives lower numbers on identical ammunition when compared to those from a midcase transducer. That's because the pressure is measured later in the event, after the pressure has already peaked. According to Jeff Hoffman, the owner of Black Hills Ammunition, military ammunition can be expected to hit 60,000 p.s.i., if measured on a Sporting Arms and Ammunition Manufacturers' Institute (SAAMI) mid-case system. Black Hills loads maximum average pressure is 55,000 p.s.i., while a 5.56x45 mm measured with a case mouth transducer has a maximum average pressure of 58,700 p.s.i.

While the 5.56x45 mm chamber is slightly larger than the .223 Rem. chamber in just about every dimension, the primary difference is throat length, which can have a dramatic effect on pressure. The 5.56x45 mm has a longer throat in the chamber than the .223 Rem. The throat is also commonly called the leade, which is defined as a portion of the barrel directly in front of the chamber where the rifling has been conically removed to allow room for the seated bullet. Leade in a .223 Rem. chamber is usually 0.085", while in a 5.56x45 mm chamber the leade is typically 0.162", or almost twice as much as in the .223 Rem. chamber. Also, the throat angle is different between the two chambers, and that can affect pressure rise and peak pressure.

SAAMI regulates cartridge overall length, but not bullet ogive design. The shape of the ogive can significantly affect how far the bullet jumps before contacting the rifling. Some 5.56 mm bullets have an ogive suitable for 5.56 chambers with the longer throat, but if they were chambered in a .223 Rem., it could result in very little, if any, "jump" to the rifling. This can increase pressures. Remember, the 5.56x45 mm already starts out at a higher pressure. If the higher-pressure 5.56x45 mm cartridge is then loaded into a .223 Rem. firearm with a short throat, the combination of the two factors can raise chamber pressures.

If you are a handloader, you must also consider that the 5.56x45 mm cartridge case may have a thicker sidewall and a thicker head, which were designed to withstand the stresses generated by the higher chamber pressures. This reduces the powder capacity of the case. If the 5.56x45 nun case is reloaded with powder charges that have proven safe in .223 Rem. cases, this reduced internal capacity can result in much higher chamber pressures.

Bottom line? It is safe to fire .223 Rem. cartridges in any safe gun chambered for 5.56x45mm. But, it is not recommended and it is not safe to fire 5.56x45 nun cartridges in a firearm chambered for .223 Rem.

In fact, the 5.56x45 mm military cartridge fired in a .223 Rem. chamber is considered by SAAMI to be an unsafe ammunition combination and is listed in the "Unsafe
Arms and Ammunition Combinations" section of the SAAMI Technical Correspondent's Handbook. It states: "In firearms chambered for .223 Rem. - do not use 5.56x45 mm Military cartridges."

There is no guarantee, however, that .223 Rem. ammunition will work in 5.56x45 mm rifles. Semiautomatic rifles chambered for 5.56x45 mm may not function with .223 Rem. ammunition because they are designed to cycle reliably with the higher pressure and heavier bullets of the 5.56x45 mm particularly with short barrels. While problems are rare, they do not indicate that the ammunition or rifle are defective. Like some marriages, they are simply incompatible.

When shooting .223 Rem. cartridges in a firearm chambered for 5.56x45 mm, it's likely that there will be a degradation in accuracy and muzzle velocity due to the more generous chamber dimensions. That's not to say that a firearm chambered in 5.56x45 mm won't be accurate with .223 Rem. loads, only that, on average, the .223 Rem. chambered firearms will be more accurate with .223 Rem. ammunition than rifles chambered for 5.56x45 mm firing .223 Rem.

Another issue is the twist rate of the rifling. The SAAMI specification for .223 Rem. is a 1:12" twist, and most non-AR-15-type rifles will use that rate. But, this is a cartridge that crosses a wide spectrum of uses, and as a result there is often a wide deviation from the 1:12" twist rate, particularly in the very popular AR-15-style "black guns." There are bullets available for the .223 Rem. that range in weight at least from 35 grs. to 90 grs. With that wide of a spectrum, one twist rate is not going to be enough.

Firearms chambered for 5.56x45 mm often have a rifling twist rate of 1:7" to stabilize the long, sleek, heavy bullets used in long-range shooting. Any rifle with a 1:7" twist rate will work best with bullets heavier than 60 grs.

On the other hand, a 1:12" twist rate (most bolt-action .223 rifles) will stabilize most bullets up to 60 grs., however some longer 60-gr. bullets will not shoot well with that twist rate. Many firearms use a 1:9" twist, which is a very good compromise that works well with most bullets up to 70 or 75 grs. The great thing is that if you have a good barrel and quality bullets, the 1:9 works well with even the lightest bullets.
What does all this mean? If you have anAR-15 type firearm with a 5.56x45 mm chamber you can shoot either .223 Rem. or 5.56x45 mm safely. If your twist rate is 1:7" you should use bullets weighing 60 grs. or heavier. If you have any rifle with a 1:12" twist you should shoot bullets of 60 grs. or less for best accuracy. If you have a .223 Rem. rifle of any type, it is not recommended that you use 5.56x45 mm ammunition.

McBuck
December 2, 2009, 06:03 PM
So...what is the chambering for a new 580 Mini-14, when the owners manual and the stamping on the gun says ".223 or 5.56" ? Ruger says the gun will accept 5.56. I have no reason to doubt that. I will probably only ever use .223 but what if I ever need/have the opportunity to use 5.56 ?


Great thread by the way ! Informative.

TexasRifleman
December 2, 2009, 06:07 PM
Mini-14's have always been 5.56 chambers, I don't believe that has changed with the new models. Their engraving a novel on the side of the rifle seems to get worse every year though :)

sandkicker
December 2, 2009, 06:40 PM
I hate to have my first post on this forum to be a disagreement, however:

Re: "Mini-14's have always been 5.56 chambers"

Should read "Mini-14's made since 1986 have 5.56 chambers"

SaxonPig
December 2, 2009, 06:40 PM
Once again, #32 covers this VERY popular topic.


223 vs. 5.56 (and .308 vs. 7.62x51).

32. There is essentially no difference between commercial .223 and military 5.56 ammo. The same is true with .308 and 7.62 ammo. The military stuff has slightly thicker brass with a tiny bit more length in the shoulder and I hear this is for strength when feeding through full-auto guns that tend to slam the rounds into the chamber violently. But otherwise, there doesn’t appear to be any difference that I have noted after many years of shooting both military and commercial ammo through my .223 and .308 rifles, both bolt action and semi-auto although with some guns with tight chambers closing the bolt on military ammo can be a bit snug. The military 5.56 ammo is loaded to very slightly higher pressures than commercial .223.

Maverick223
December 2, 2009, 07:21 PM
Should read "Mini-14's made since 1986 have 5.56 chambers"I am pretty sure that is not true either, as I believe the "target" model is chambered for .223, and 5.56 is not recommended.

:)

Boba Fett
December 2, 2009, 07:29 PM
It is a popular misconception that military 5.56 ammo is loaded to higher pressures than commercial .223 but it is not.


And yet SAAMI's site says it is unsafe and not to use 5.56 in a 223.

http://www.saami.org/Unsafe_Combinations.cfm


Fulton Armory doesn't think it's really a good idea either:
http://www.fulton-armory.com/556-vs-223-Chambers.htm
Here's the problem. Many NATO cartridges have bullets that will become jammed into the rifling of a SAAMI chambering (the throat is too short). This is VERY DANGEROUS, for a great number of reasons.

From Winchester:
http://web.archive.org/web/20080505215048/http://www.winchester.com/lawenforcement/news/newsview.aspx?storyid=11
Paul Nowak
5/4/2001
.223 Rem VS 5.56mm

There are a lot of questions about these two cartridges. Many people think they are identical - merely different designations for commercial and military. The truth is that, although somewhat similar, they are not the same and you should know the differences before buying either cartridge.

* The cartridge casings for both calibers have basically the same length and exterior dimensions.
* The 5.56 round, loaded to Military Specification, typically has higher velocity and chamber pressure than the .223 Rem.
* The 5.56 cartridge case may have thicker walls, and a thicker head, for extra strength. This better contains the higher chamber pressure. However, a thicker case reduces powder capacity, which is of concern to the reloader.
* The 5.56mm and .223 Rem chambers are nearly identical. The difference is in the "Leade". Leade is defined as the portion of the barrel directly in front of the chamber where the rifling has been conically removed to allow room for the seated bullet. It is also more commonly known as the throat. Leade in a .223 Rem chamber is usually .085". In a 5.56mm chamber the leade is typically .162", or almost twice as much as in the 223 Rem chamber.
* You can fire .223 Rem cartridges in 5.56mm chambers with this longer leade, but you will generally have a slight loss in accuracy and velocity over firing the .223 round in the chamber with the shorter leade it was designed for.
* Problems may occur when firing the higher-pressure 5.56mm cartridge in a .223 chamber with its much shorter leade. It is generally known that shortening the leade can dramatically increase chamber pressure. In some cases, this higher pressure could result in primer pocket gas leaks, blown cartridge case heads and gun functioning issues.
* The 5.56mm military cartridge fired in a .223 Rem chamber is considered by SAAMI (Small Arm and Ammunition Manufacturers Institute) to be an unsafe ammunition combination.



Before buying either of these two types of ammunition, always check your gun to find what caliber it is chambered for, then buy the appropriate ammunition. Most 5.56mm rounds made have full metal jacket bullets. Performance bullets - soft points, hollow points, Ballistic Silvertips, etc. - are loaded in .223 Rem cartridges. Firing a .223 Rem cartridge in a 5.56mm-chambered gun is safe and merely gives you slightly reduced velocity and accuracy. However we do not recommend, nor does SAAMI recommend, firing a 5.56mm cartridge in a gun chambered for the .223 Rem as the shorter leade can cause pressure-related problems.



So, yes...you can shoot 223 from 5.56, but shooting 5.56 from 223 is unwise and possibly dangerous.

Now, some people may shoot 5.56 from 223 and not have issues...yet.

I just wouldn't want to be the one person that proves why manufacturers and organizations warn against it.

SaxonPig
December 2, 2009, 10:32 PM
Case dimensions are identical. I have shot hundreds of military 5.56 through several commercial bolt and semi-auto rifles without incident. That's all I know.

http://stevespages.com/jpg/cd223remington.jpg

http://stevespages.com/jpg/cd556nato.jpg

I did make a slight correction. The military ammo is loaded a tad hotter. I doubt it's enough to make a difference. Yes, the SAAMI lawyers tell them to say using 5.56 in a .223 is unsafe. All reloads are unsafe, too, you know.

wishin
December 3, 2009, 06:56 PM
I am pretty sure that is not true either, as I believe the "target" model is chambered for .223, and 5.56 is not recommended.

My target model is marked .223 caliber on the receiver.

Maverick223
December 3, 2009, 09:18 PM
My target model is marked .223 caliber on the receiver.How does it shoot? I get the feeling that despite the target name it still isn't a bench gun. Not trying to bash them (don't know about the target variant, but the new ones are much improved over the former series), as I rather like the Mini, just wondering.

:)

wishin
December 3, 2009, 09:25 PM
I've been very pleased with the groups using 68 gr. Ultramax. Getting consistent 3/4' 3 shot groups from a bench rest with bipod, with an occasional flyer. I tried many different factory brands and various bullet weights. It loves the Ultramax loads.

Maverick223
December 3, 2009, 09:47 PM
Not bad at all, glad to hear that it shoots well. You need to post a group in Krochus' Mini Match...you might just win. ;)

EDIT: In case you're interested, Here (http://www.thehighroad.org/showthread.php?t=485140) is a link to the match.

possum
December 4, 2009, 07:49 AM
welcome to thr.

for the type of training i do and in the context of which i train with my ar, the accuracy difference if there is one is not somthing that i am worried about, and honestly something that i have never had an issue with.

Offfhand
December 4, 2009, 08:55 AM
Just curious, has anyone ever heard of 5.56 ammo causing problems in a .223 Rem bolt rifle?

rcmodel
December 5, 2009, 12:56 PM
Yes, I have.

Many years ago, SAKO made some Vixen's with .223" bores instead of .224".
They were also tight chambered in .223 Rem.

Along the same time, Remington was making .223 Rem Model 40-X target rifles with very tight .223 Rem match chamber dimensions.

There were reports of blown primers in both guns when shooting higher pressure 5.56 ammo in them.
No harm was done to the shooters.

That is the only two instances I have ever heard of.

I hate to have my first post on this forum to be a disagreement, however:
Re: "Mini-14's have always been 5.56 chambers"
Should read "Mini-14's made since 1986 have 5.56 chambers" I hate for you to be wrong too, but you are.

All Mini-14's, since day one, have been chambered for .223 and 5.56.
It says so in the owners manual.

Mini-14 Series 180 1974 - 1977.
http://www.ruger-firearms.com/products/_manuals/mini14-180.pdf

The only exception is the current Target model which is chambered for .223 only.

rc

greyling22
December 5, 2009, 06:34 PM
so if I took 5.56 brass and reloaded it in a .223 die set with .223 load data (not a hot load, just a middle range one) would it be safe to shoot in a .223 chamber?

Maverick223
December 5, 2009, 09:41 PM
so if I took 5.56 brass and reloaded it in a .223 die set with .223 load data (not a hot load, just a middle range one) would it be safe to shoot in a .223 chamber?I don't see why not, and it should last a little longer than .223 brass. Furthermore, I have never heard of or seen "5.56 dies", as the case is identical (with exception of thickness). I can tell you that .223 dies work just fine for my 5.56 (brass and rifle).

:)

Boba Fett
December 5, 2009, 09:47 PM
so if I took 5.56 brass and reloaded it in a .223 die set with .223 load data (not a hot load, just a middle range one) would it be safe to shoot in a .223 chamber?


From post 14:
The 5.56 cartridge case may have thicker walls, and a thicker head, for extra strength. This better contains the higher chamber pressure. However, a thicker case reduces powder capacity, which is of concern to the reloader.

Other than that I don't see any reason it wouldn't work.

Mags
December 5, 2009, 09:57 PM
If a 5.56 case is thicker than 223 brass how can a 223 bullet fit in a 5.56 case?

wishin
December 5, 2009, 10:18 PM
I believe both use a .224 diameter bullet.

Maverick223
December 5, 2009, 10:29 PM
If a 5.56 case is thicker than 223 brass how can a 223 bullet fit in a 5.56 case?I don't believe that the thickness at the neck is any different from the .223, and the bullet diameter is definitely the same (.224).

:)

chuckusaret
December 5, 2009, 10:36 PM
Hey guys, SAAMI has been saying since the late 1970's not to use 5.56 in weapons marked .223 only and I take their word and don't do it.

SAAMI info: http://www.thegunzone.com/556v223.html

wishin
December 5, 2009, 10:47 PM
Post#8 by W.E.G. in this thread, does a good job of explaining the differences and interchangeability.

BrianB
December 5, 2009, 11:11 PM
I shoot both with zero problems. Accuracy is not noticeably different, but then again, I'm not competing for match accuracy anyway. I'm told that my 5.56 ammo is louder than my .223 ammo. From behind the barrel, with ear protection, I can't tell.

Bottom line is to get a 5.56 chamber. Then you're completely fine.

Maverick223
December 5, 2009, 11:37 PM
Edited post 28 to read: "...don't believe that the thickness at the neck is any different...", mistakenly said that the neck was of a different thickness.

:)

greyling22
December 5, 2009, 11:40 PM
I was just asking because I still had a few 556's loaded as 223's and didn't know if it was safe to shoot them in my new 223 bolt gun. sounds like I am good to go.

Maverick223
December 5, 2009, 11:47 PM
sounds like I am good to go.With a .223 chamber (such as yours) I am not positive, but I believe you will be fine. With a 5.56 chamber (such as the O.P.) I know you're safe with 5.56 and .223, as well as 5.56 resized using .223 dies.

:)

Kurt_D
December 6, 2009, 12:26 AM
223 vs. 5.56 (and .308 vs. 7.62x51).

32. There is essentially no difference between commercial .223 and military 5.56 ammo. The same is true with .308 and 7.62 ammo. The military stuff has slightly thicker brass with a tiny bit more length in the shoulder and I hear this is for strength when feeding through full-auto guns that tend to slam the rounds into the chamber violently. But otherwise, there doesn’t appear to be any difference that I have noted after many years of shooting both military and commercial ammo through my .223 and .308 rifles, both bolt action and semi-auto although with some guns with tight chambers closing the bolt on military ammo can be a bit snug. The military 5.56 ammo is loaded to very slightly higher pressures than commercial .223.

I don't know what you consider "slightly" but in the case of 5.56 NATO vs. .223 from AR w/ 20" 5.56 chambered barrel the 62gr .223 loads clock in at ~3000fps while M855 clocks in at ~3200fps. I haven't chronoed it yet but M193 should clock in at 3300+ fps from a 20" barrel while 55gr .223 normally clocks in at 3200 fps from a 24" barrel. That's a very big slightly.

7.62 NATO and .308 are the opposite so far as max pressures are concerned but I don't think there's much difference here commerically unless you get into the hot and heavy or handloaded .308 loads. If you where to beleive the reloading manuals though a 150gr bullet can be pushed to 2900fps when hitting max .308 pressures while typical 7.62 NATO loads clock in at what 2700fps?

You also have to look at, in the case of .223/5.56, what's using what chamber? Semi-autos typically use 5.56 chambers (or a version of) while bolt guns typically use .223 chambers. It's pretty well known that gas guns usually show pressure signs sooner than bolt guns and that bolt guns are usually stronger action wise. I doubt other than a hard to extract case every once in a while it would matter much to fire 5.56 in a .223 chambered modern bolt gun.

With 7.62 and .308, I wouldn't run some hot and heavy .308 loads through a mil surp 7.62 gun. I think this is a more dangerous situtation because the rolls are reverse and the semi-auto is getting the higher pressure ammo. Add that to the fact that mil surps are usually older guns not designed for anything near what we can load today. Now their newer decendants such as new DSA FAL, PTR-91, M1A, AR-10, etc. I doubt there's much issue.

SpeedAKL
December 6, 2009, 12:33 AM
High quality factory .223 will out-shoot 5.56 milsurp with boring regularity so whatever minute accuracy differences there may be in shooting SAAMI .223 out of a 5.56 chamber will be more than made up for.

The only military issued ammo that will approach civilian .223 match loads is the Mk.262 ammo that SOCOM has been known to use. This is loaded with the 77-gr sierra match king bullet. A very similar load is available through Black Hills.

dogngun
December 6, 2009, 08:25 AM
Chambers are usually a little larger in military rifles to allow for slight variations in ammo, dirt, etc, and the brass is slightly thicker, and primers slightly harder.

I doubt there is much other difference.

mark

SaxonPig
December 6, 2009, 09:55 AM
Kurt D

I looked up the chamber pressures and they were like 2,000-3,000 PSI greater on the 5.56. That's not really a whole lot (maybe 4% or so) and is probably mostly due to the thicker case on the military rounds. I would not be surprised if the ammo manufacturers used the same powder charge for commercial 223 and military 5.56 but the cases for each are different in thickness causing the slightly elevated pressure in the military rounds. Most reloading manuals warn to reduce reloads slightly with military cases due to the added thickness raising pressures a tad.

Of course gun makers and ammo makers issue the usual dire warnings on advice of their lawyers. But like I said, I have used commercial and military ammo interchangeably in my 223 and 308 rifles, both auto and bolt, without any issues. I have never HEARD of anyone having any sort of problem.

An early 223 rifle made before the advent of the longer 68 grain bullet might be a concern due to lack of free-bore with such ammo, but I think recently made rifles have enough chamber length to use them. You always want to be aware of overall cartridge length in any rifle.

Offfhand
December 6, 2009, 10:35 AM
REMODEL, thanks for getting back with response to my question. It's easy to understand why the Sako would have a pressure problem, not just with 5.56 Mil ammo but with standard .223 as well. The same with the 40-X if it has a BR dedicated chamber and neck specs. The Remington custom shop BR neck is .246" unless specified otherwise by customer. This requires turning the case necks to .010" for ample, yet close fit. Standard neck diameter of 5.56 and commercial .223 ammo averages close to .248." Which makes it difficult to force into a BR chamber, requiring a hard, determined push on the bolt to get it closed, if at all. A squeeze that tight would certainly result in blown primers, etc. with any otherwise standard 5.56 or .223 load. But in both examples the situations described would seem to be more related to non-standard chamber or barrel specs. Where I work we have a number of "slave" .223 Cal rifles used for evaluating 5.56 Mil and .223 commercial loadings. These have standard SAAMI chambers and I'm not aware of there having been any problems. Which is why I'm trying to get reports from outside observers such as yourself. Thanks again

happygeek
December 6, 2009, 11:32 AM
Wait, the SAAMI unsafe combinations linked to (http://www.saami.org/Unsafe_Combinations.cfm) says that a 9mm Luger (Parabellum) chamber is unsafe with 9mm NATO (Military) :confused:

I thought that 9x19mm Luger, aka Parabellum, was 9mm NATO. I'll have to Google this now. At any rate, the only 9mm I own is a Beretta 92FS and I'm pretty sure it's 9mm NATO.

rcmodel
December 6, 2009, 12:49 PM
Same difference.

9mm NATO is loaded to higher pressure then American SAAMI standard pressure 9mm Luger.

It's more like +P SAAMI spec ammo I suppose.

Whatever it is, your Beretta 92, and most all other 9mm pistols with a military design background were made to shoot it.

As for .223/5.56 pressure comparisons?
Can't do it, because the military testing measures pressure in a different place in the barrel then SAAMI specs call for.
Whatever GI pressure specs you find is Apples & Oranges when compared to commercial ammo pressure.

rc

happygeek
December 6, 2009, 03:56 PM
The only 5.56x45mm rifle I own is a Sig 556 and it says 5.56 NATO right on the side of the thing :)

Come to think of it, didn't the Seals crack the slides on some of the early test M9s by firing +P 9mm ammo?

Quick lookup on Wikipedia

Prior to its widespread adoption by the U.S. military, questions were raised in a General Accounting Office report after an incident where a slide failure on a Beretta 92SB injured a Naval Special Warfare member[3] and two more failures were later observed in additional testing. These failures included both military and civilian Beretta models with very high round counts and after investigation they were deemed the result of ammunition supplied by the U.S. Army which exceeded the recommended pressures specified by NATO and by Beretta, but nonetheless provoked a modification in the M9 design to prevent slide failure from causing injuries.

rcmodel
December 6, 2009, 04:05 PM
The ammo that was cracking slides was over-pressure & out of NATO spec to start with.

Following the slide cracking incidents, a change was made to a different power among other things.

rc

happygeek
December 6, 2009, 04:39 PM
Ahhh, good to know. I know the 92FS model has that, ummm, thing that stops the slide from flying off the back at you if it does crack.

kenkel98
July 9, 2011, 11:12 PM
Ok guys,

I don't mean to beat a dead horse about this but...

I have a Ruger Mini-14 Ranch built in 1999. It is labeled .223 on the receiver. I haven't taken it apart to see if the barrel is stamped 5.56, but according to the manual, it will shoot both the .223 and the 5.56.

I have a Colt AR-15 SP1 built around 1973 and it is stamped .223 on the lower. Nothing stamped on the barrel, not even the twist rate.

I have been shooting both .223 and 5.56 ammo in the Ruger for the last 15 years or so. Of course, I really don't shoot it that often. It has probably had less than 1000 rounds put through it but still, no problems with the 5.56 ammo. That's not to say it won't happen, but...

The AR has had quite a few more than that run through it. Both 5.56 and .223. I have always used 55 gr. ammo assuming the twist rate is probably 12.1. Again, never had a problem. Again, not to say it won't happen, but...

I have not seen any difference in accuracy, keeping in mind I have not locked these guns into vices and shot them at 500 yards. I normally shoot between 75 and 150 yards.

I have been a gun "nut" for over 35 years and consider myself very knowledgable. But, I have learned a lot here tonight. I worked part time in a gun store for years, mostly just for the fun of it, but I never knew about the differences between the .223 and the 5.56 rounds. I had always been told that the 5.56 was the military or NATO designation for the .223 and that they were the same round. And I was in the Air Force!! Of course, I only had to shoot the M-16 twice during my 4 years.

I plan to reload the .223/5.56 and have all the dies, powder and bullets to do so.

Everytime I login to this web site I learn something new.

Just my 2 cents worth..

Thanks again THR for being here for us.

K

ugaarguy
July 9, 2011, 11:34 PM
but according to the manual, it will shoot both the .223 and the 5.56. There's the answer on your Mini-14.
I have a Colt AR-15 SP1 built around 1973 and it is stamped .223 on the lower. Nothing stamped on the barrel, not even the twist rate.
It's probably a 5.56 chambered bbl, being an older Colt, but that's a bit before my time. I owned an SP-1 of 1986 vintage (IIRC that's when the Marine who sold it to me told me he bought it new) which was stamped .223 on the lower, but had the standard C MP 5.56 1:12 stamped on the bbl forward of the FSB. Have you taken off the handguards to see if the barrel is stamped underneath them?

isc
July 10, 2011, 12:10 AM
This is the most overblown "controversy" in the gun world and amounts to little more than two old ladies arguing over whether a dress is black or Navy blue.

It doesn't matter. .223 Remington and 5.56x45 are interchangeable designations for the same round and one can't measure the difference between cartidges loaded to the respective specifications doesn't exist.

Using highly sensitive and precise tools one could likely measure the minute variations in chambers, but you can't measure the difference in the cartridges themselves.

ugaarguy
July 10, 2011, 12:30 AM
It doesn't matter. .223 Remington and 5.56x45 are interchangeable designations for the same round and one can't measure the difference between cartidges loaded to the respective specifications doesn't exist.

Using highly sensitive and precise tools one could likely measure the minute variations in chambers, but you can't measure the difference in the cartridges themselves.
The chambers, throats, and leade angles DO matter. Running true 5.56 spec ammo in a .223 chamber that's on the tight side of the SAAMI spec. WILL cause problems. Yes, I've seen it.

M1key
July 10, 2011, 02:08 PM
Colt SP1s were 556 Nato chambered. Owned three, with the first one back in the mid-70's. All shot LC mil surp 5.56.

I guess gun makers are still stamping whatever they want on barrels and receivers, further adding to the confusion.

As posted earlier, even Saigas have ".223 Rem" stamped on their receivers and magazines. The manual lists the cartridge as ".223 Rem (5.56x45)".

M

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