I do not think they approve of guns, but allow the NATO headstamp on ammo that meets certain specs and the p99 manual states not to use +p ammo. I am not sure if this is true, but I was under the impression that 9mm NATO rounds are a bit hotter and have a harder primer (for submachine guns).
The civilain manual may just state this to keep down exessive wear and tear and not to prevent a dangerous condition. I would be interested in knowing if Walther has a different set of specs for LE and military gun manuals or if they even have a different manual.
My understanding was that yes, NATO has a standardized 15,000 round torture test that is applied to all submitted firearms to NATO countries. However I've only ever seen this referred to in a few articles. The Beretta USA sight states that the Cougar passed this test. I remember reading an article several years ago when the Glock-19 was said to have passed this test. It also involves inclement weather testing etc. There is also spec testing from what I gather ie. You have to be a standard NATO caliber (9mm, 5.56etc). At the moment the only reference I can find is the Beretta Law Enforcement catologue which states that the Cougar is "NATO Approved". But there is other material out there I just did not save it as i was not really interested in the Cougar or Glock at the time. (anyone else know what I'm talking about? Help!
Ok I've got Walther Customer service looking into it, we'll see what they come up with and I'll advise if anyone is interested. Fredette whoever that is sent me an email saying they were researching this.I know Springfield sent my buddie a ton of material when he asked.