7.62x51 and 308 Winchester

[StarMetal]

I finally found it. Was looking for an article on the difference between the 7.62x51 and the 308 Winchester. Here is it:

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.


Joe

[fourarmed]

Good post, Joe. I've heard so much ranting on that topic over the years, you wouldn't believe it. Or maybe you would. Where did you find it?

[StarMetal]

fourarmed,

I found it on that website I posted in the .338 M1 Garand post.

I heard Mike Venturino write something along time ago about this...and just recently he's been ridiculed for not being smart. He's not dumb.

Joe

[twotoescharlie]

this momths garand collectors magazine has the complete article on this.


TTC

[mike in co]

308 winchester:
chamber
go gage 1.630
no-go 1.634
field reject 1.638

us 7.62 x 51
chamber
go gage 1.635
field reject 1.6455....!!!!!!

saami 308 chamber pressure
map 62,000 psi (max ave press)
mpsm 66,000 psi
min proof press 83,000 psi
max proof press 89,000 psi

usa 7.62 x 51
chamber pres
max 50,000 psi
proof 67,000 psi......


close but not the same....

[Larry Gibson]

308 winchester:
chamber
go gage 1.630
no-go 1.634
field reject 1.638

us 7.62 x 51
chamber
go gage 1.635
field reject 1.6455....!!!!!!

saami 308 chamber pressure
map 62,000 psi (max ave press)
mpsm 66,000 psi
min proof press 83,000 psi
max proof press 89,000 psi

usa 7.62 x 51
chamber pres
max 50,000 psi
proof 67,000 psi......


close but not the same....

Excuse me but TM 9-1305-200 dated June 1961 states that the pressure (PSI) for the M80 7.62 NATO Ball; "the average chamber pressure may vary from 45,000 psi to 65,000 psi, depending on the temperature."

Seems to fit in with the SAAMI specs and is close enough to win the cigar. They are the same if one compare REAL specs from the TM and REAL SAAMI specs. The chamber dimensions are different in military weapons for obvious reasons. The chamber dimensions have nothing to do with cartridge dimensions or pressures in test barrels.

Don't buy the myth, the 7.62 and the .308 Win ARE dimentionally and pressure wise the same.

Larry Gibson

[Char-Gar]

my understanding is the .308 Winchester "no-go" guage is the 7.62 Nato "go guage". The ammo is the same.

I have used hundreds of LC 7.62 Nato cases in the .308 and they do require a healthy reize and a small base die helpful if the cases were fired in an automatic weapon.

[mike in co]

Excuse me but TM 9-1305-200 dated June 1961 states that the pressure (PSI) for the M80 7.62 NATO Ball; "the average chamber pressure may vary from 45,000 psi to 65,000 psi, depending on the temperature."

Seems to fit in with the SAAMI specs and is close enough to win the cigar. They are the same if one compare REAL specs from the TM and REAL SAAMI specs. The chamber dimensions are different in military weapons for obvious reasons. The chamber dimensions have nothing to do with cartridge dimensions or pressures in test barrels.

Don't buy the myth, the 7.62 and the .308 Win ARE dimentionally and pressure wise the same.

Larry Gibson

larry,
its not unusual for DESIGN and REAL data to vary. my data is design, yours is what is expected in real life .

look at the chamber specs...they are not the same. i agree, most people will never get into a problem with the two, but i dont want to be in the 1% problem group!

[StarMetal]

Just like the article says: 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.

......and I can see we are having that debate here.

Larry the military chamber is different not because it's a military chamber, with all the military idiosyncronies they have for such reasons, but because the 308 Winchester and the 7.61x52 were developed years apart. The 7.62 didn't come out first and then Winchester decided to commercialize it, such as what happen with the 5.56 and the 223 Remington. Yes the 308 and 7.62 are close, so close that like the article said it's hard to find true 7.62 ammo and that there are, have been, and will be instances where firing 308 commercial ammo in a military rifle could get you into trouble.

I guess we'll have to ask God this, along with who killed Kennedy, when we finally meet him.

Joe

[Larry Gibson]

Just like the article says: 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.

......and I can see we are having that debate here.

Larry the military chamber is different not because it's a military chamber, with all the military idiosyncronies they have for such reasons, but because the 308 Winchester and the 7.61x52 were developed years apart. The 7.62 didn't come out first and then Winchester decided to commercialize it, such as what happen with the 5.56 and the 223 Remington. Yes the 308 and 7.62 are close, so close that like the article said it's hard to find true 7.62 ammo and that there are, have been, and will be instances where firing 308 commercial ammo in a military rifle could get you into trouble.

I guess we'll have to ask God this, along with who killed Kennedy, when we finally meet him.

Joe

The military chambers are different not because they are military but because they are made with extra toleraces for functional reliability. The military (other than some special rifle teams) do not use reloaded ammunition. Therefore the overly expanded cases are not a consideration.

There are only two instances where the firing of .308 commercial ammo in military rifles may cause problems. Only one of those may damge the rifle. The first is the use of W-W cases. These are too thin in the web area and a case head seperation may result. There is usually no damage here just the potential for a stuck case in the chamber. The second is if .308 Light Magnum or Exteded Range ammo is used in gas guns. This ammo has too high of a gas port pressure and damage to the gun may very well result. If you want to discuss the FR7 that's fine but be advised I've been tracking several of them owned by soldiers who have been shooting both M80 ball and commercial .308 Winchester ammo in them without any problems particularly bolt lug set back as most often reported.

"Yes the 308 and 7.62 are close, so close that like the article said it's hard to find true 7.62 ammo"

I'm not sure what the problem with finding "true 7.62" ammo is, I've been finding it for years. The Army issues it to me to shoot. It is also readily available around most every gun show. It is also issued to state rifle teams. You can find M80, M62, M118, Special Ball M118 and even some M118LR if you try. Not really that hard to find.

I don't find the 7.62 vs .308 to be a dilema at all. It is nothing more than a myth perpetuated by opinion. I deal with facts. Winchester developed the cartridge for the military and released it before it was "adopted" by the military. The reason for that was simply because the M14/M60 had not been fully developed or fielded for it's use. Winchester already had the M70 in production. That's a no brainer there.

Don't buy into the myth; they are the same.

Larry Gibson

[versifier]

"A rose by any other name...." "Soil" in the bag, but dirt on your hands. "Manure" in the compost pile, but **** when you track it on the rug. "Sensitive child" when described by his mother, spoiled little animal to the rest of the world. I have personally seen a lot of dead deer to whom any percieved difference between the two is a moot point. They don't argue about it anyway.

[Bob S]

My copy of the NATO STANAG is MIA at the time being, and I don't have the complete SAAMI spec, but I do have the Mil Specs.:

http://img.photobucket.com/albums/v76/BobS1/MilC46931header.jpg

http://img.photobucket.com/albums/v76/BobS1/M80pressurereqmts.jpg

Resp'y,
Bob S.

[Bob S]

http://img.photobucket.com/albums/v76/BobS1/MilC46477BHeader.jpg

http://img.photobucket.com/albums/v76/BobS1/M60Proofcartridgepressurereqmt.jpg

Resp'y,
Bob S.