is there such thing as commercial 7.62 NATO brass

[510dat]

I'm sure this is a dumb question, but does this exist, or do M14/M1A reloaders just use .308 brass?

I understand that the primary difference between the two rounds is the length and thickness of the brass, so I assume that reloading for the two would be slightly different as well.

Or am I just seeing problems where there are none?

[ciscosixgun]

Commercial 7.62 is .308 I think you answered your own question. A lot of reloaders dont like military brass because it has crimped primers and requires an extra step when processing brass.

I dont know what the difference is between 7.62 and .308. I can only guess that the .308 chamber will have tighter tolerances than 7.62. If 7.62 has thicker walls than .308 it could give you higher pressures with the same powder charge you are using in .308.

I know that SAMMI says its unsafe to fire 5.56 in a .223 chamber and I do know the difference between a .223 and 5.56 chamber as well as the pressure difference between the two. But I have no clue when it comes to 7.62 and .308. Maybe someone else can enlighten us I would be interested in finding out the difference.

I do know this. When I was taking a class on accurizing varmit and sniper rifles I saw a lot of bolts close on a .308 no go gage. Even on high dollar so called custom rifles. I guess the idea is to allow their rifles to chamber everything out there including 7.62. Needless to say I did a barrel set back on my rifle to minimum headspace tolerances and I dont know if it shoots any better. But thinking it does has a huge phycological effect.

[jandmtv]

.308 has higher chamber pressure than 7.62x51, i think

[rayra]

The commerical / civilian loadings usually do, at least from US manufacturers.

As to the extra work / step, it's only once. And with something like a Dillon swage it's really easy.


eta - my Speer No11 Reloading manual combines both .308 and 7.62 Nato into a single entry and makes no mention of any substantive difference in the cartridges

[glockman19]

I buy Winchester 3031 NATO stamped 7.62, 147 grain ammo.

[postal]

Big difference in pressure. 308 is rated over 10k psi higher than 762.

762 chambers are usually VERY long in the throat as well for different types of ammunition to chamber correctly.

If you reload for a 762 chamber, stay low on your powder charge compaired to 308 hot loads.
You can shoot 762 in a 308, though it may fail to chamber on a match chamber.. if it will fit, you can shoot it safely.

Do NOT shoot commercial 308 in a 762- it could blow up in your face.

[buffybuster]

The external dimensions of the brass is essentially the same, HOWEVER the chamber dimensions, pressure ceiling, method to measure headspace are different. As a result, 7.62 brass may be a tight fit in a 308Win chamber and conversely 308Win brass may be excessive headspace in a 7.62 chamber.

The reason is that Winchester brought the 308Win to market before the 7.62Nato specifications had been fully finalized. So Winchester did there thing and Army Ordanance did there thing. The major differences are in the chamber dimensions (7.62Nato having a much longer throat and the headspace is measured at different points along the shoulder) and the pressure ceiling with the 308Win being approximately 10K psi higher. Though this is difficult to quantify since Winchester originally submitted CUP pressure measuring method and Army Ordanance used PSI which do not have a direct correlation.

Internally, the 7.62Nato cases generally have thicker walls and less capacity than 308Win cases, so you can't just use 308Win data in 7.62 cases.

Headspace spec's are along these lines (rule of thumb, if you want exact dimensions look them up)
(~ means close to)
308Win GO ~ Borderline Minimum 7.62
7.62 GO ~ 308Win NOGO (Maximum Headspace)
7.62 NOGO ~ 308Win FIELD (Excessive Headspace)
7.62 FIELD = 308Win DANGEROUSLY EXCESSIVE Headspace

Ramifications:

New 7.62Nato ammo in 308Win chamber: First thing to do is take some measurements of the case length to insure that it is not beyond the 308Win Max Case Length. Usually this is not a problem, but 7.62Nato has been made by many different sources and specs can vary. If it is at or above Max safe that for a 7.62Nato chamber or pull if for components. If it's below Max, and it will chamber fully and the bolt will close all the way, then you're most likely good to go. Herein lies the problem. I've shot 7.62Nato in a 308Win bolt action and it takes more pressure to cam the action closed and as long as I get the bolt all the way down it's OK. A semi-auto with a 308Win chamber, it may not fully close with 7.62Nato ammo and it could fire out of battery or without the lugs fully engaged, which could shear the lugs. As a result, I don't shoot 7.62Nato in a 308Win semi-auto.

New 308Win ammo in 7.62Nato chamber: Your major concerns with this combination are: possible excessive headspace and excessive pressure. The headspace on new commercially produced 7.62Nato rifles is generally set on the lower end and is safe with 308Win ammo (manufacturers know these rifles will be used with both) and the metallurgy has improved to be safe with the higher pressures. Herein lies the problem. Many 7.62Nato chamber rifles are military surplus (FAL, STG58, HK, CETME, FR7&8, Converted Lee-Enfields, Ishapore Enfields, etc) All these rifles are chambered somewhere along the 7.62Nato chamber spectrum, also some of these actions were borderline with the lower 7.62Nato pressure specification. Shooting 308Win in these rifles could create several dangerous conditions (excessive headspace, excessive pressure, excessive gas port pressure for semi-autos, potential case failure due to thinner spec'd case. Also, the Spanish FR-7, some FR-8's and CETME's were not designed for 7.62Nato at all. For a brief period Spain adopted a lower pressure cartridge, dimensionally identical to 7.62Nato but with a lower chamber pressure (40-45Kpsi). Also, the Ishapore Enfields and converted Lee-Enfields may not be strong enough and experience bolt set back. The semi-autos will close just fine with 308Win ammo but might have excessive headspace.