After engaging in YET ANOTHER argument online about 9mm NATO specs, I’d like to just say my piece once right here and then reference it. I have STANAG 4090 right in front of me; it’s not that hard to read, it’s just that most people have not.

American shooters have had access to M882 for years. This is excellent ammo, and I run a lot of it through compensated pistols. Unfortunately, this has also led to many shooters deciding that M882 is the NATO spec, and nothing else works. This is absolutely not the case, and I would be glad to tell you why after the break.

STANAG 4090 has some basic requirements for NATO-compliant 9mm ammo that we care about:

1. It’s got to be 9mm, and gives the dimensions as such.
2. Precision must be at least 3″ at 50yds.
3. Bullet weight must be between 108gr and 128gr.
4. Energy must be between 400ft/lbs and 600 ft/lbs.
5. Mean pressure cannot exceed 37k PSI and 230MPa. Individual rounds can be as hot as 42.7k PSI and 265MPa.
6. There are some primer specs. I don’t know if I’d call them hard primers, but they’re definitely not soft.
7. It needs to be water-proof.
8. It needs the NATO cross marking on the headstamp.

If someone hands you some 9mm ammo that doesn’t meet one of these requirements, it is not NATO spec ammo. Conversely, if someone hands you some 9mm ammo that’s different than M882, that does not mean it is not NATO spec ammo.

Here are some quick takeaways:

1. 115gr 9mm ammo is not automatically “out of NATO spec”. In fact, the new Winchester XM1152 (FMJ) ammo is in the energy spec because they run it at 1300fps.
2. Claims that NATO spec ammo must be +P are not quite true, but are probable given the energy requirements. Chances are good that it’s not +P+, but strictly speaking, individual rounds might be due to loading variances.
3. Velocity and energy are measured from a standard proof barrel of 7.85″ length. This is substantially longer than your pistol’s barrel, and thus it is likely that your pistol’s barrel will not produce results as spectacular as the NATO spec demands. HOWEVER, pressures will still be higher than most commercially loaded bulk ammo.