One hundred rounds of Winchester "White Box" bulk-packed ammo went through the Walther PPX this morning, bringing the total to 1200. The gun experienced two malfunctions, each of which really rates its own post.
The second one was the more interesting because in the middle of a rapid-fire string, I got a dead trigger. Looking at the pistol explained why:
I can't count this malfunction against the PPX, since the round was subsequently tested in my Gen 3 Glock 19 and one of my M&Ps and wouldn't fully chamber in either.
As a side note, this malfunction tied the gun up hard; if somebody had been shooting at me, I'd have been hosed. This is the sort of thing that's an argument for backup guns and/or chamber-gauging your carry ammo. You'll find horror stories on the 'net about ammo that looks like this, warning you to carefully examine rounds before loading them, but the defect with this particular round would not have been picked up by the naked eye.