The Firearm Blog publishes a reader report from a gentleman claims his Walther P5 was damaged by shooting 9mm NATO ammo. My only semi-issue/concern with the story is that the Walther P5 was designed for NATO spec ammo, so I would be more likely to blame poor quality control for the breakage than the ammo.
Now, an interesting side note to this story: my Para Tac-5 actually prefers the hotter NATO loads, and +P loads to standard pressure stuff. I have no idea why, but the only times the gun has failed to cycle properly have been while using standard powered 115 grain FMJ ammo. Whenever I’ve used 124 grain NATO loads, or 147 grain +P loads from Black Hills, the gun runs just fine. From an engineering standpoint, I’d hazard a guess that because the slide on the 1911 pattern gun is a little on the heavy side, the gun likes the hot loaded ammo because the extra pressure ensures that enough energy is imparted to the slide to to make stuff run. If this is the case, then I could make it function more reliably with lighter loads by switching to a lighter recoil spring…but then I wouldn’t be able to shoot my hot 147 grain “anti-bowling pin” loads through it.