Wednesday, August 6, 2014

This is Handy

Don't know about you guys, but I've personally asked "is it OK to shoot 7.61 NATO in my .308 Win rifle".  I've read on it before, but this graphic from is a handy reference.  And while this is supposed to be a gun blog (I've even got the Tee-shirt), I sure haven't been very good at keeping up the gunny content lately. 

.308 vs. 7.62x51
380 vs. 7.62x51

I printed this out for the reloading area.

So the rule is you can shoot 7.61 NATO in a .308Win gun, but not the other way around.  If you have an AR-15 like everyone else, it's the opposite of 5.56 NATO and .223 Rem where you can shoot both in the 5.56x45 NATO gun and not the .223 gun.  


  1. Except that the "50,000 psi" for NATO is a typo, that's really CUP.

    Actual max pressure for NATO in psi is 60,000. .308 in CUP is 52,000.

    The amusing thing about this doom and gloom is every mil rifle that gets pictured as failing from ammo is shooting mil-surplus and not commercial.

  2. Plus, the proof round is 40% over-max pressure, so a mil spec gun is designed to take 84,000 psi. (Even if the 50k CUP number was psi it'd still be within proofing at 70,000 for the 62,000 .308.)

  3. One wonders why. Did the designers and engineers get together over a few drinks and try to come up with some way to screw with people and maybe cause some accidents fatal and non-fatal? Were they simply oblivious of the other round when the second of these two (7.61/308 & 5.56/.223) was created? Did someone stand up at the design meeting and point out the risks and then was voted down? How do such risky situations exist when the people who create them are presumably intelligent?

  4. Anon - I don't work in the arms biz, but I know that in electronics systems and aircraft the Mil stuff takes on odd characteristics because they impose odd requirements the commercial stuff can't meet.

    As for why the commercial guys don't then adopt the mil specification ammo, that's probably due to cost.

    Angus - have you emailed the guys who made the chart,

    I've encountered the CUP vs. PSI issue on this ammo before.

    If I get a minute, I'll post the guidance I've had on this topic for a few years.

  5. If this was a real problem, there would be reports all over the web. There have got to be people, lots of people, bubba included, shooting 308 and 7.62 on a more or less interchangeable basis. This incompatibility issue has been noted for years, and yet I have never actually heard of a blown up gun.

  6. DPMS will void the warranty on a 5.56 cal rifle is any but domestic ammo is used. The warranty is a bit over the top, but liability is very important to them I'm sure.

  7. I'm 5 weeks late to this party, but "grams" should be "grains" in the diagram noting the case weights.

  8. Thanks, daniel_day! It's amazing none of us caught that, especially considering all the comments.

    185 grams! That's almost half a pound. (crunch crunch) 6.5 ounces.

    Quite a round.