.308 win vs 7.62x51

[mchaley]

It's pretty well known that these are (almost) the same round. I've heard you can use both in a .308 win. I've done some looking around and found that the 7.26x51 is a bit smaller in some dimensions:

7.62x51:
Parent case .300 Savage
Case type Rimless, Bottleneck
Bullet diameter 7.82 mm (0.308 in)
Neck diameter 8.58 mm (0.338 in)
Shoulder diameter 11.35 mm (0.447 in)
Base diameter 11.84 mm (0.466 in)
Rim diameter 11.94 mm (0.470 in)
Rim thickness 1.27 mm (0.050 in)
Case length 51.05 mm (2.010 in)
Overall length 69.85 mm (2.750 in)
Rifling twist 1:12"
Primer type Large Rifle
Maximum pressure 415 MPa (60,200 psi)



.308win
Parent case .300 Savage
Case type Rimless, Bottleneck
Bullet diameter 0.308 in (7.8 mm)
Neck diameter 0.343 in (8.7 mm)
Shoulder diameter 0.454 in (11.5 mm)
Base diameter 0.470 in (11.9 mm)
Rim diameter 0.473 in (12.0 mm)
Rim thickness 0.050 in (1.3 mm)
Case length 2.015 in (51.2 mm)
Overall length 2.800 in (71.1 mm)
Rifling twist 1/12
Primer type Large Rifle
Maximum pressure 62,000 psi (430 MPa)


edit: Bolded the greater dimensions



SO the question:
even though it's off by a small amount, is it still alright to use a 7.62x51 in a .308 win?

[MTechnik]

Originally Posted by mchaley

It's pretty well known that these are (almost) the same round. I've heard you can use both in a .308 win. I've done some looking around and found that the 7.26x51 is a bit smaller in some dimensions:

SO the question:
even though it's off by a small amount, is it still alright to use a 7.62x51 in a .308 win?

I think the answer is "yes, so long as you aren't reloading"

[mchaley]

So it IS still safe to use both types of ammunition in a .308 win rifle?

Just want to make 100% sure

And what if you were reloading? (I dont plan on it)

[General Geoff]

Anything chambered for .308 Winchester will happily eat up any 7.62 ammo.


With a milsurp chambered in 7.62, however, you want to check your headspacing before you shoot a lot of .308 through it. 7.62 go/no-go chamber spec tolerance is really loose, which is fine when using thick 7.62 brass, but might end badly with some thinner .308 brass.

[CoyoteJack]

The reloading issue as I understand comes from once fired brass actually stretching when the smaller round in shot in the larger chamber. The reloaded brass can then be problematic I suppose.

[mchaley]

Originally Posted by General Geoff

Anything chambered for .308 Winchester will happily eat up any 7.62 ammo.


With a milsurp chambered in 7.62, however, you want to check your headspacing before you shoot a lot of .308 through it. 7.62 go/no-go chamber spec tolerance is really loose, which is fine when using thick 7.62 brass, but might end badly with some thinner .308 brass.

How would I check headspacing?

[skyjerk]

Originally Posted by CoyoteJack

The reloading issue as I understand comes from once fired brass actually stretching when the smaller round in shot in the larger chamber. The reloaded brass can then be problematic I suppose.

As I understand it, its the 7.62 chamber that may be ever so slightly larger
with regard to headspace, but is the same in other respects.
This would suggest that .308 ammo can be readily used in a 7.62 NATO rifle, but that if you use 7.62 NATO ammo
in a .308 rifle you could have issues because the cartridge could conceivably be too long for the headspace in the chamber.

That said, with regard to firing 7.62 ammo in a .308 rifle I am just parroting what I have heard and have no direct personal experience.

I do know the other way around though.

I have a 7.62 NATO chambered [evil black] rifle (DPMS LR-308C) and I shoot .308 ammo through it all the time.



At least 75% of that .308 ammo is ammo I reloaded myself.

As long as you dont max out the pressure of the loads its fine.
Max pressure loads aren't as accurate anyway so its no loss.

I load 168 grain Sierra BTHP with Hodgdon Varget.
Hogdons data for this bullet/powder combo recommends starting loads at 42 grains and the max at 46 grains.

44 is giving me the best accuracy, I have no pressure problems, and I can
reuse those cases again a few times.

[Qtrborecrazy]

Warning only use ammo made for your rifle. You will find it stamped right on the barrel for a reason. If your fire forming that is another story. Read owners manual before blowing ones face off. Ask any lawyer.

Qtrborecrazy

[skyjerk]

Originally Posted by Qtrborecrazy

Warning only use ammo made for your rifle. You will find it stamped right on the barrel for a reason. If your fire forming that is another story. Read owners manual before blowing ones face off. Ask any lawyer.

Qtrborecrazy

DPMS clearly states that you can use any commercially loaded .308 ammo in
their 7.62 NATO chambered rifles.

[mchaley]

but not so much a .308 win stamped rifle...
Reason I'm asking is because I might have some 7.62x51 mixed into my ammo pile. Plus if it works - 7.62x51 is usually cheaper.