Cartridge confusion

[BlueTrain]

This is something that I expect has been talked about before but I couldn't find it here. Here is my question.

I am confused about cartridge interchangeability. What are the limitations on cartridge use for these rifles and cartridges:

.308 Winchester and 7.62 NATO military production ammunition (from anywhere), in both civilian sporting rifles and military issue rifles (including, I guess, the M1A).

.223 Remington and 5.56 NATO, same as above.

I have never seen any reference to .30-06 Springfield not being completely interchangeable in any rifles or any other cartridge in the same way. I am not referring to otherwise confusing cartridges like .303 Savage and .303 British but chiefly to the two above.

I have likewise never heard of any differences with 7.62x39 either, although I suspect there are differences between civilian production and foreign military production, particularly in the hardness of the primers, that might make a difference in shooting your prized SKS. Same with the 7.62x54r.

Any comments?

[DimitriS]

The 308 and the 7.62 are the same case dimentions. As is the 5.56mm and the 223. The difference being in the leade of the millitary chambers and the comercial chambers and also the pressures they are ment to operate with.

Millitary chambers have a larger leade allowing the bullet to "jump" after it gets released from the brass. Commercial chambers do not have this larger leade so they can be more accurate but it also means Millitary ammo might develop over pressure because of it.

If you were to take a batch of 7.62mm it "should" work fine in a 308 chamber but there might be problems with over pressure and the like. So its a hit or miss you might end up hurting your weapon because of how the chambers were designed. Now thats not to say you cant pull the bullets off them and use the cases to reload and not have a single problem. Mind you I never heard of a M1A or a M14 (in SA) have a problem with the old military rounds I think the chambers must have been kept the same as the old M14 specs for the 7.62mm thats why it can handle it.

5.56mm on the other hand can be had in chambers designed to take both it and the 223 without a hicup on some AR's and from what I have read if your AR states it can take the 5.56mm it normally can take both as the leade in the 5.56mm is longer then the 223 so it will still allow the 223 to chamber.

The 30-06 chambers can use the M1 or M2 ball I belive. I never heard of a problem of using 30-06 chambers with the old ammo for the Garand. Or using the Garand's chamber for the 30-06

Dimitri

[Donaldo]

I'm pretty sure there would be no problem using 7.62 NATO or .308Win in an M1A. The website for Springfield Armory states the M1A is chambered in "7.62NATO (.308 Winchester)".

If I had a rifle chambered for .308, I would probably refrain from using 7.62NATO without a lot of research. As a side note, I wouldn't use M60 (machine gun) ammo in a 7.62NATO chamber. Even though the dimensions are the same, the MG ammo has higher operating pressures to help work the belt feed system.

[BlueTrain]

Thanks for the comments.

You used to hear a lot of comments about "sub-machine gun" ammuntion that shouldn't be used in pistols. This would be referring to 9mm, I suppose, but somehow I doubt there is any special sub-machine gun or machine gun ammuntion. It runs contrary to the whole purpose of standard ammuntion. I certainly don't remember hearing anything about that when I was in the service. However, I also understand that NATO 9mm ammuntion and some, if not most, WWII 9mm ammuntion was and is loaded to a higher pressure than is common to most commercial ammunition.

Along these same lines, Sweden, I believe, used 6.5mm ammuntion in rifles, carbines and automatic rifles, which in that case was the Browning. Yet they used a different caliber in their heavy machine guns, which would now be called a medium machine gun. To allow for a common ammuntion in machine gun units, they used rifles chambered for the same round as the machine gun, which was an 8mm but not an 8mm Mauser (which they also may have used).

Also on the subject of ammuntion, I believe I read recently here or elsewhere that snipers handload their own ammuntion, which is hard to believe. They probably select their own ammuntion, however, which is something else altogether. Again, providing special ammuntion for snipers may be a good idea but it cancels out any reason to use the same ammuntion that everybody else does--except when you run out of that special ammuntion.

When do you suppose the military practice of oversized chambers started? It would tend to make you wonder how all military cartridges, American, at least, could become instantly popular here, as they all have ever since cartridges were introduced, including the .50 BMG.

[Jim Watson]

There is no doubt that 7.62/5.56 military chambers are larger in most dimensions than commercial .308/.223. I think this came about along with the increase in rate of fire and the formation of wide alliances. A modern military autorifle or machine gun will be shot long, hot, dirty, and with ammunition from who knows where. We are warned of the risks of getting a maximum military cartridge in a minimum commercial chamber and of getting a minimum commercial cartridge in a maximum military chamber. I don't know the incidence of actual malfunctions or damaging accidents.

We are frequently warned that .308 commercial ammunition is or may be loaded to higher chamber pressure than 7.62 military. If so, it is something that was changed on the fly because when they were introduced as USGI and the commercial equivalent, they were nearly the same. I think it is due to changes in pressure measurement methods and reporting. If .308 were really allowed to be 20% hotter than 7.62 wouldn't the sporting rifles be delivering substantially higher velocity?

As far as dedicated SMG ammunition goes, when Lee Jurras was making headlines with high velocity hollowpoints, he ran samples of all the WW II 9mm ammunition he could round up through the Super Vel pressure gun. None were any higher than standard pistol ammo. I suspect a 100 grain sintered iron bullet over cheap wartime powder gives a loud report and bright flash so you THINK it is real powerful. On the other hand, there is some hot, hot, hot Hirtenberger 9mm out there. The L7A1 designation makes me wonder if the British might have wanted it to soup up their Sterlings.

Yes, the Swedes used 6.5x55 rifles, BARs, and machine guns. Their heavy (Browning!) machine gun was in 8x63, a cartridge used only by Sweden that I know of. They also had some 98 Mausers in 8x63 with muzzle brakes. I can only assume that was so the ammo humpers in the heavy weapons squad could reload their rifles off the ends of MG belts.
If you think the Swedes had it bad - and they weren't even fighting - look at the Japs. They started the war with 6.5 Arisaka rifles and LMGs, and a semi-rimmed 7.7mm HMG. I guess the 6.5s weren't putting the Chinese down fast enough because they went to a different rimless 7.7mm for rifles and some machine guns. But they were already fighting a war and had to keep the 6.5s going, too. So they had three different infantry calibers to support. And the Nip navy had Lewis guns in still a different 7.7mm which was really .303 British.
Italy tried to change rifle calibers after Ethiopia, but were so hurting that they gave up on the 7.35 Carcano and went back to 6.5 almost entirely. Along with 8mm Breda machine guns.

I don't think snipers handload their own ammunition, they have enough to do as it is. Sniper ammo is normally military match produced by an arsenal or contractor.

[BlueTrain]

I haven't heard Lee Jurras's name or Super Vel mentioned in ages! It sort of takes you back to when people were cutting down S&W model 39's.

This is getting off the topic somewhat but I also understand that people used to have trouble getting their Lugers to work, back when people still were shooting Lugers, because the American made ammuntion was not hot enough to make them work reliably. I have sometimes wondered it ammuntion companies reduce the loads they produce after so many years. Or are advertised velocities slightly exaggerated?

[Olaf]

The .308 Win. and the 7.62 x 51 (7.62 NATO) have ALMOST identical case dimensions....they are not exactly the same, but so close as to not matter, in most cases. The .223 Rem. and the 5.56 x 45 (5.56 NATO, now)....the same story.

The general rule for interchangebility is: either can be used in COMMERCIAL rifles. However, it is generally NOT a good idea to use commercial .308 Win. in a military rifle. Two reasons for this - 1) the chambers on the military rifles are just a bit oversized...to ensure reliable feeding/ extraction.....and 2) often, commercial ammo is loaded hotter than military stuff, again to ensure reliability (in the military rifles).

I used 7.62 NATO in my .308 Remington 700's all the time...with never a problem. I'm not sure that i would be a good idea to try military ammo (slightly larger cases) in a semi-auto commercial rifle - I've heard that jambs can be common.

[woodland]

I used some 7.62 South African surplus ammo in my 700VS, and I think it was a little too hot. It was hard to lift the bolt handle and rotate the bolt after firing a round. All I can think is it was too hot. If I remember right, the neck of the case was all black, too. It has been awhile.

[The British Soldier]

We were using 9mm Hirtenberger in our Browning Pistols in Northern Ireland; which might be the reason that we had so many stress cracks in the slide!

[Mike Irwin]

The reason you never saw any difference with the .30-06 as you have with the 7.62/.308 and .223/5.56 is because the U.S. government developed it at Frankford Arsenal.

The 7.62 and 5.56 were both developed by commercial entities (Winchester and Remington, respectively) who developed their own set of commercial parameters outside of what the military wanted.

[DimitriS]

Mike,

Thanks for the insight!

I must have forgotten that the 30-06 was built inhouse for the US millitary

Dimitri

[Jack O'Conner]

7.9mm and 8X57 are one and the same. Just different names as built in different European countries.
Jack

[Odd Job]

So, gents, if I undertand the .223 Rem vs 5.56x45 cartridge right:

1) The .223 Rem was the precursor to the 5.56 NATO cartridge and is the same physical dimensions (according to Barnes' Cartridges of the World 10th edition, which I have here).

2) The .223 Rem cartridges can be fired in the military weapons, but SAAMI advised that the 5.56x45 NATO cartridges should not be fired in .223 Sporting rifles because the chambers are of different shapes for the military and sporting rifles (also taken from Barnes' book)

What I don't understand is: if the cartridges are the same physical dimensions then why have a difference in chamber design at all? That information I can't find.

[jhgreasemonkey]

either can be used in COMMERCIAL rifles

Yes. Many many people do this if that helps put you at ease. Once in a while you will hear someone talk about a potential problem doing this but those are the engineer types who are stuck on numbers and formulas. I second that either can be used in commercial rifles. Carefull with military rifles though. Have heard of some firsthand problems using .223 in 5.56 military rifles. and as stated above using .308 in 7.62 nato military rifles. Buy yourself a decent .308 bolt hunting rifle and shoot all the 7.62nato you want.

[Odd Job]

@ jhgreasemonkey

Carefull with military rifles though. Have heard of some firsthand problems using .223 in 5.56 military rifles.

As a matter of interest can you tell me which military rifles those were? I have experience only with the South African R5 (a short course organised for me by a Flying Squad member) and as far as I can recall we had boxes of NGA .223 Rem cartridges for that shoot.

Edit: ja we were using NGA .223 Rem cartridges

[jhgreasemonkey]

Hold the press! After looking into it I may have given bad advise because it seems I had it backwards. Here is the correct version .223 in military rifles okay. 5.56 in comercial rifles not good. I believe I was correct concerning the .308 and 7.62x51 which is the other way around. Here is something I looked up when I began questioning myself about the 5.56mm.
5.56 mm NATO vs. .223 Remington
In January 1979, the Sporting Arms and Ammunition Manufacturers’ Institute (SAAMI) advised that 5.56 x 45 mm military specification ammunition is generally not safe to fire in .223 Remington-chambered rifles (which are mainly civilian sporting rifles). [1] The chambers of weapons intended to take the NATO round are oversize relative to the civilian weapons to allow for greater variation in production (and hence reliability), and 'hotter' loads containing more propellant. By contrast, SAAMI-specification chambers are manufactured tighter (for accuracy), and 5.56 mm NATO ammunition, at the larger end of the manufacturers' tolerances, will be too tight and result in overpressure. This can cause excessive wear, or even theoretically cause parts of the rifle to rupture. Conversely, civilian .223 ammunition is perfectly safe to use in military rifles.[2]
There I went making fun of engineering types and now I have to put my large foot into my even bigger mouth.

[5whiskey]

.308 and .223=SAAMI specifications
7.62 and 5.56=NATO specs

Go to MA parts (they make AR kits), and check out their FAQs. They give the most thorough scientific explanation of this that I know of. Armalite also gives a decent comment on their website FAQs.

MOST rifles today are made to fire either or. Armalite actually splits the difference between SAAMI and NATO specs. SAAMI chambers are tighter than NATO, so a SAAMI chambered rifle will inherently be more accurate. A NATO chambered rifle will fire even the loosest and crapiest ammo on full-auto without a hiccup (in theory, anyway). Since NATO chambers are a bit larger than SAAMI, there is a concern that ammunition manufacturers should be more precise with their tolerances for SAAMI designated ammunition. Since NATO designated ammo doesn't have AS precise of a tolerance, you could find a round that is slightly large for the smaller SAAMI chambers. This COULD cause the bolt to not fully lock upon firing, but more often than not you'll run into a round that doesn't want to extract and it won't be a big deal.

Bottom line, read the owners manual to the firearm in question, it should specify if this particular rifle will fire NATO ammo safely. If not specified in the owners manual, look at their website and email the question if it's not an a FAQ post.

[Eghad]

From Fulton Armory..... M1A/M14 FAQ

What's the Difference between .308 Winchester & 7.62x51mm NATO?
by Clint McKee and Walt Kuleck

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dumb question i alway thought these 2 ammos where interchangeable but some have told me otherwise whats the story??? jim

Hi, Jim,

This is a perennial topic, kinda like ".45 vs. 9mm" or "Best Guns & Loads for Deer."

They are not the same.

They are the same.

They are not the same, 'cause the .308 Win was released by Winchester several years before the Army standarized the T64E3 as the 7.62MM. You'll get an endless discussion of pressure specs, endless because SAAMI and the Ordnance Dep't measured pressure in different, unrelateable ways. Howver, the chamber drawings are different.

They are the same, 'cause nobody (and Clint's been looking for many years!) makes 7.62MM ammo that isn't to the .308 "headspace" dimension spec. So 7.62MM ammo fits nicely into .308 chambers, as a rule.

But in some 7.62MM rifles the chambers are long (to the 7.62MM military spec), notably the Navy Garands with 7.62MM barrels. Thus, using commercial ammo in such a rifle is not a good idea; you need stronger brass. Use military ammo or the best commercial only, e.g., Federal Gold Medal Match.

Most of the time it's a distinction without a difference. But if you intend to shoot .308 commercial in a military arm chambered for 7.62MM, first check the headspace with .308 commercial gauges first. You may get a surprise.

Best regards,

Walt Kuleck
Fulton Armory webmaster


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Clint, What's the difference between .308 Winchester & 7.62x51mm NATO?

Jerry Kuhnhausen, in his classic Shop Manual (available from Fulton Armory; see the M1 Rifle Parts & Accessories or M14 Rifle Parts and Accessories Pages under Books) has published a somewhat controversial recommendation concerning .308 Winchester and 7.62x51mm NATO ammo, headspace & chambers. I broached the subject with him some months ago. He had his plate full, so we decided to chat on this in the future. When we do I'll report the results of our conversation.

I completely agree with Jerry that if you have a chamber with headspace much in excess of 1.636 (say, 1.638, SAAMI field reject), you must use only U.S. or NATO Mil Spec Ammo (always marked 7.62mm & with a cross enclosed by a circle) since the NATO mil spec calls for a far more "robust" brass case than often found in commercial (read .308 Winchester) cartridges. It is precisely why Lake City brass is so highly sought. Lake City brass is Nato spec and reloadable (most NATO is not reloadable, rather it is Berdan primed). Indeed, cheaper commercial ammo can fail at the 1.638 headspace (e.g., UMC) in an M14/M1 Garand. Many military gas guns (e.g., M14 Rifles & M60 Machine guns) run wildly long headspace by commercial (SAAMI) standards (U.S. Military field reject limit for the M60 & M14 is 1.6455, nearly 16 thousandths beyond commercial (SAAMI) GO, & nearly 8 thousandths beyond commercial (SAAMI) field reject limit!).

I also agree that 1.631-1.632 is a near perfect headspace for an M14/M1A or M1 Garand chambered in .308 Winchester. But I think that it also near perfect for 7.62mm NATO!

I have measured many, many types/manufacturers of commercial and NATO ammo via cartridge "headspace" gauges as well as "in rifle" checks. If anything, I have found various Nato ammo to be in much tighter headspace/chamber compliance than commercial ammo. Indeed, sometimes commercial ammo can not be chambered "by hand" in an M14/M1A with, say, 1.631 headspace (bolt will not close completely by gentle hand manipulation on a stripped bolt, although it will close & function when chambered by the force of the rifle's loading inertia), though I have never seen this with NATO spec ammo. I.e., if anything, NATO ammo seems to hold at the minimum SAAMI cartridge headspace of 1.629-1.630, better than some commercial ammo!

So, why set a very long 1.636 headspace in an M14/M1A or M1 Garand? It probably is the conflict mentioned above. Military headspace gauges say one thing, SAAMI headspace gauges say something else, as do the spec's/compliance covering ammo. In a court of law, who will prevail? I think Kuhnhausen gave all those who do this work a safe way out. However, I believe it not in your, or your rifle's, best interest. Whether you have a NATO chambered barrel (M14/M1 Garand G.I. ".308 Win."/7.62mm NATO barrels all have NATO chambers), or a .308 Winchester chamber, keep the headspace within SAAMI limits (1.630 GO, 1.634 NO GO, 1.638 FIELD REJECT). This subject is a bit confusing, and for me difficult to explain in a one way conversation!

Clint McKee

[BlueTrain]

Well, to be on the safe side, I'm going to stick with rimmed cartridges only, from here on out. (Just kidding).

[Edward429451]

tagged for reference.

http://www3.sympatico.ca/shooters/7_62vs308.htm