I bought two Walther PPQ M2 long slide pistols a few weeks ago and just got them out to the range today.  I quickly noticed something odd on the brass cases - both guns leave a definite line all the way around the case near the case mouth.  The ammo was reloaded, but there was nothing wrong with it (no pressure issues, no sizing issues, nothing).  After inspecting the gun, I see that there is a small line all the way around the chamber, which must be what's leaving the line on my brass.  Is this normal?  If so, why does Walther do it?

I know the picture isn't clear, but that's because my camera won't focus.  Trust me, there is a definitive line all the way around the case.
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Now that you mention it, I see that line in my chamber too.  I take it that it's nermal.

It's normal. Search for "stepped 9mm chamber" with your favorite search engine. Apparently it was an early modification of the 9mm Luger chamber that is only occasionally used nowadays and Walther tends to incorporate it into their pistol chambers. While I can't speak with firsthand experience, the general consensus is that it shouldn't effect reloading the brass, if that's a concern.

Thanks guys, I appreciate your help.