Please explain .308 to me

[blackmind]

and please forgive me if this is not in an appropriate forum. I tried to pick the most likely place.

I have seen plenty of reference to .308 as a serious caliber, a "sniper" caliber, a hunting caliber... I am trying to figure out if this is what I want in my next rifle or not, since all I have is a Colt Match Target HBAR (think "post-ban AR-15") and an SKS in 7.62x39.

Some stuff I've read has confused me. Is .308 the same as 7.62? I could swear I've gotten that impression. There are more 7.62 calibers than just 7.62x39, right? So, is .308 "just .308"? A caliber all to itself?

Thanks for clarification, if you can provide it.

-blackmind

[Jim Watson]

.308 is USUALLY shorthand for .308 Winchester which is the commercial designation of 7.62 NATO = 7.62x51 as used in M14, FN-FAL, etc. military rifles and offered in about every make of sporting rifle.

[leadcounsel]

see my earlier post about the .308 same as 7.62

[DanV1317]

The .308 is most closely related to the 30-06, but the heaviest weight bullet that is useful in the .308 is 200gr. The 30-06 (shoots in a m1 garand) is 220gr i think. Balistics for the .308 are pretty close the 30-06. While 7.62x39 (shoots in sks) is nice, the .308 is more accurate and had a better range to it. It is also an amazingly accurate caliber, as many people shoot these out to 600-700 yards accuratly. You will find alot of bolt actions rifles chambered in .308.

the 7.62x39 would be good for smaller deer. But you sure can get this ammo pretty darn cheap.

[Bullet94]

blackmind

Edited ( deleted) to the better knowledge of Jim Watson.

[Jim Watson]

Bullet94:
Please try to furnish the new guys correct information.
7.62mm = .300" which is the BORE (land) diameter of most .30 caliber rifles.
.308" is the barrel GROOVE diameter and bullet diameter used in most and converts to 7.82mm. Which is seen only in the name of the 7.82 Lazzeroni Warbird that I know of.

[Tim R]

The M-1 didn't shoot 220 gr bullets either. M-2 ball uses a 150/152 gr. bullet. M-2 ball was developed for the M-1 Garand. Ap rounds used I believe 163 gr. bullets. Match used 173 gr. bullets.

.308 Winchester is the comm version of 7.62 Nato They are simular to the point there is no real difference unless you like to argue.

[Kayser]

A point worth noting about .308 vs. 7.62, which can similarly be made about .223 vs. 5.56 mm. They are -not- the same cartridges.

The difference lies in the thickness and density of the military 7.62 brass vs. the standard .308 brass. The 7.62 is thicker, has a lower powder capacity and is going to behave differently in your rifle. If you buy a Remington .308 (for example) and fire a couple of 7.62mm rounds from it, the first thing you'll notice is that when you try to work the bolt, it's going to feel like it's seized shut. It'll require a ton more force than you're used to to extract the round. Upon firing, the case mouth is going to expand much more aggressively and form way too tight of a grip in the chamber. A couple of these, and you'll think "this can't be good for my snazzy new varmint rifle".

Bottom line - the practical, no-guesswork approach is to assume 3.08 and 7.62mm are different calibers and get on with your life

[blackmind]

So the .308 which is the same as 7.62x51 NATO is NOT the same 7.62 that goes through my SKS?

And if I go looking for a semi-auto rifle, like an AR-10, in .308 as I've seen them advertised, that's ".308 Winchester"?


-blackmind

[DimitriS]

Yup you got it all figured out

Dimitri

[Kayser]

So the .308 which is the same as 7.62x51 NATO is NOT the same 7.62 that goes through my SKS?

Not quite.

.308 win is NOT the same as 7.62x51 Nato.

The SKS fires 7.62x39 which is different from both.

In other words, from a practical perspective the 3 are all different. I will go ahead and add that in the world of AR's there are several places that make rifles which will work fine with .308 and 7.62x51. However, aside from this complex world of black rifles, assume they are different calibers.

[Cowled_Wolfe]

Just whipped this up... It's not *perfectly* to scale, but it gives a half-decent idea of the comparative cartrige sizings... Later on, I'ma make one that's a bit more accurate.

Btw... I KNOW .308/7.62x51 ain't the same, but they're the same on the outside so I'm just putting 'em as the same for the pic...

Wolfe.

EDIT: Forgot due credit... Original pictures borrowed from http://www.special-warfare.net/data_...s/cart_02.html ... Used photoshop to get the rounds to scale(ish).

[Acegoesbang]

theres 7.62.39 7.62.54 7.62.51 7.62.25

[Unclenick]

The NATO rounds are loaded to higher pressure than SAMMI spec .308 Winchester. You can fire the two interchangeably in the M14 or M1-A or in a Palma match gun, but some lighter bolt action .308's can get into trouble with the NATO load. I have fired the .308 out to 1000 yards using the 175 grain Sierra MatchKing over 44.6 grains of Varget in a Winchester .308 case from a 24" tac rifle. The 168 Grain Sierras fall sub-sonic at about 700 yards and start to tumble and keyhole.

Originally, the Palma match (1000 yards), was fired with ammunition provided by the host country, which sometimes was a NATO round. In 1992 the U.S. took a turn as host, and the U.S. team got Winchester to make special near-balloon head cases with extra powder capacity and got Sierra to make a special 155 grain bullet (the maximum weight the rules allowed) and had these custom loaded for the match, including 10,000 practice rounds to be shipped in advance to attending teams. It proved so superior to all previous Palma ammunition that the Palma rules now require the Sierra bullet be used. I'm not sure about the other components?

.30 M1 ball was a 172 grain boat tail load adopted in 1925 to replace the original 30-36 which was a 150 grain bullet fired by fast burning Pyro DG powder. The new loading took advantage of the then-new progressive burning IMR powder. Garand had first built a primer setback operated rifle, but the pressure curve of the new ammunition coupled with Frankford Arsenal's adoption of the crimped primer put an end to the concept.

Garand moved to a gas operated design. The first of these that resembled the ultimately adopted Garand was developed for the .276 Pederson cartridge. Later it was redesigned for M1 ball, in part because the military wanted to be able to use their existing stocks of M1 ammo in the new rifle, but also because of the results of other tests conducted by the military. Hence the U.S. Semiautomatic Rifle, Caliber .30 M1 adopted in 1936 was the M1 firing version of the Garand rifle, or, M1 Garand, for short.

The 152 grain spitzer fired by IMR powder came later and is designated M2 Ball. AP ammunition has a 168.5 grain bullet and became the standard combat issue because it penetrated helmets and body armor better, and "Ball" wound up being relegated to practice.

At the time Maj. Gen. Julian Hatcher wrote his "Book of the Garand", 1948, the military's caliber .30 military ammunition of the basic 1906 dimensions (the Springfield 1903 had been chambered in 30-30 until 1906) was summarized by Hatcher as follows:

Cartridge___Bullet Weight___Bullet Shape__Jacket Material__Peak Pressure____M.V.___Extreme Range


.30 M1906___150 grains_____Flat-based____cupro-nickel____50,000 psi____2,700 fps____3409 yds
.30 M1______172 grains_____Boat-tail______gilding metal____48,000 psi____2,647 fps____5500 yds
.30 M2______152 grains_____Flat-based____gilding metal____50,000 psi____2,805 fps____3500 yds
.30 AP______168.5 grains____Flat-based____gilding metal____50,000 psi____2,775 fps____3500 yds


The Garand action is stronger than Mauser or Springfield bolt actions, but the operating rod can be bent by excess gas pressure at the muzzle, so heavy, slow bullets have to be loaded down to fire in it, or the gas cylinder plug has to be modified to vent the excess pressure. The re-work of that basic action shape for the M-14 included getting the gas piston to be self-limiting in how much gas it would admit, so the M14 can handle a greater range of pressure and bullet sizes without modification.

Nick

[Zekewolf]

The external dimensions of .223 are different from 5.56mm, which is not the case with .308 Win./7.62 NATO.

[RugerOldArmy]

"The NATO rounds are loaded to higher pressure than SAMMI spec .308 Winchester."

Incorrect. It is the other way around. It is confusing because the military and SAMII measure pressure differently.

Reduce loads developed in .308 Win cases when using the thicker 7.62x51 Military cases.

Op rod concerns have also been noted, using .308 Win hunting loads in semi-autos designed for lighter military bullet weights.

Then again, in Military semi-autos, chamber dimensions are often different, looser, and the thicker military brass is safer.

[RugerOldArmy]

Here are the differences:

.308 Winchester chamber headspace gauges:
GO: 1.630"
NOGO: 1.634"
FIELD REJECT: 1.638"

US Army 7.62x51 chamber headspace gauges:
GO: 1.635"
FIELD REJECT: 1.6455"

SAAMI .308 Winchester chamber pressures:
MAP: 62,000 psi
MPSM: 66,000 psi
Minimum Proof Pressure: 83,000 psi
Maximum Proof Pressure: 89,000 psi

US Army 7.62x51 chamber pressures:
Maximum: 50,000 psi
Proof pressure: 67,500 psi

7.62x51 NATO pressure data from: TM 43-001-27 "Army Ammunition Data Sheets Small Caliber Ammunition" and headspace data from Kuhnhausen's M1/M1A shop manual

.308 Winchester data from ANSI/SAAMI document Z299.4-1992, "Pressure and Velocity, Centerfire Rifle Sporting Ammunition"

[lonniemike]

FWIW, the Russian rifle's 30 caliber or three line,7.62X39 and 7.62X54 ammo usually has a bullet diameter around .310" unlike our 30 caliber in about.308" diameter.
RugerOldArmy I believe that the US army pressures that you cited should have been in CUP not psi. A lot of old info was published incorrectly using CUP and PSI interchangeably. IIRC, 308=52K CUP, 7.62NATO=50K CUP, 30'06=48K CUP

[Archie]

Blackmind: I have seen plenty of reference to .308 as a serious caliber, a "sniper" caliber, a hunting caliber... I am trying to figure out if this is what I want in my next rifle or not, since all I have is a Colt Match Target HBAR (think "post-ban AR-15") and an SKS in 7.62x39.

Some stuff I've read has confused me. Is .308 the same as 7.62? I could swear I've gotten that impression. There are more 7.62 calibers than just 7.62x39, right? So, is .308 "just .308"? A caliber all to itself?

Thanks for clarification, if you can provide it.

At the most basic level, .308 is the inch measurement for the diameter of the rifle barrel. Normally, the groove to groove diameter is .3085" and land to land is .308". In metric, this is referred to as 7.62mm; except as Brother Watson mentioned, 7.62 actually measures .300". In U. S. rifles, this is lumped into the "30 caliber" group. Included are .30-30 Winchester, .30-40 Krag, .30 M1 Carbine, .30-06, .308 and all the .300 Something-or-other Magnums.

Bullet weights run from about 110 grains to 250 grains. Obviously, not all bullets are useful in all cartridges.

In addition, there are the European - normally Russian or Soviet - rounds in more or less thirty caliber. The .30 Russian, or 7.62x54R is the old Tsarist rifle round of the Mosin-Nagant. The 7.62x39 is the same bore diameter. The cases are different, and the bullet weights differ as well. In practise, the Russian 30s are more on the order of .311 than .308 in bore diameter. Then there are the European handgun rounds of .30 Mauser, .30 Lugar and .30 Tokarev. They too, are .311" bore size.

Don't forget the manufacturer's tolerances in all these instances.

Now... to sort this all out in your head... get a current reloading manual - like Speer's or Lyman's or Hodgdon's or Hornady's and just look up the rounds in question. The book will show you dimensional drawings and give you some background on the various rounds - as well as actual bore diameters. The diagrams make a lot more sense than these verbal descriptons.

[T. O'Heir]

Hi, blackmind. "...Is .308 the same as 7.62?..." Yes. 7.62mm is metric for .308". Same thing. However, .308" is the diameter of the bullet. Cartridge designations rarely have anything to do with the bullet diameter though. For example, the 7.62 x 54 Russian isn't .308" diameter. It's .311. Nor is the barrel of a .303 British, .303". It's .311" to .315".
No offense, but you sound like you need some basic firearm education. S'ok. Everybody has to start someplace. (all I have is a Colt Match Target HBAR) Geezuz, what a shame. I know guys who would give you their daughters for an H-Bar. You're foolin' with us aren't you?)
Anyway, go buy a copy of Hatcher's Notebook. About $30 at your local gun shop. Buy a reloading manual while you're at it, even if you don't reload, there's a wealth of info in them.

[DimitriS]

I know guys who would give you their daughters for an H-Bar.

From rifle calibers to rifle trading Sorry but I laughted too much when I read this eventhough I dont have a daughter as I am unmarried and all I couldnt see myself trading one of my "future" daughters away for a rifle

Maybe this is something that you learn only by age and actually having kids ??

Dimitri

[308LAW]

most of the time I wouldnt trade my daughter for a whole bunch of guns, but there are times when I would give all my guns just to get rid of one for a while.LOL

[DimitriS]

lol 308Law

Why dont you hire a baby sitter or something to get them out of your hair for abit ??

Its alot cheaper and wont make you regret getting rid of your guns

Dimitri

[Dave R]

Here's the short version of the 7.62X51 NATO vs. .308 Winchester comparison.

Its OK to shoot military 7.62X51 NATO ammo in a commercial .308 rifle. I do it regularly.

Its NOT OK to shoot commercial .308Win ammo in a millitary 7.62X51 rifle. Although if you handload, and use military brass, you can dial in a load that works. Speer No. 13 has some military loads "starred" for use in M-14 and other 7.62NATO rifles.

[Unclenick]

RugerOldArmy,

I took a look at specifications and it appears you are correct that the U.S. loads are below SAMMI pressure specs, being 50,000 P.S.I. vs 62,000 P.S.I. (piezo transducer measurement, not C.U.P.). My assumption that the reverse was true came from personal experience with some NATO loads from Portugal. In my M1A they ran very hot, flattening primers and expanding the case heads by over a thousandth, despite the heavy hard brass. No commercial ammo ever did that. Nonetheless, I should know better than to extrapolate from one anecdotal experience.

That said, it is probably the case that much commercial ammunition is actually loaded well below SAMMI maximum to keep their insurance company lawyers happy. So, I would still caution people against assuming a gun that fires commercial ammo will necessarily fire NATO ammo just as happily. I could have had a bad lot, but the eternal caution to watch for pressure signs applies no matter whose ammo you shoot.

Dave R,

You are right that a lot of loose military chambers will not digest commercial ammo happily. I've seen rough military chambers hang on to brass hard enough that the extractor tears chunks of rim off soft commercial cases. However, a lot of military style weapons chambered for target shooting have chambers that are tight and will digest commercial match loads successfully. Heavy bullets, high energy powders, and Hornady Magnum Light loads should not be used in a Garand without modifying the gas cylinder plug to bleed off some of the extra pressure, or a bent op-rod could result. The M14 and M16 and their civilian versions can handle a range of bullet weights and pressures much better. I don't know much about other military style gas guns, so I would be cautious about what I put through them.

Nick