Just to add to the confusion, There was a run of Walther P-99's that used Smith and Wesson slide, machined to Walther specs, and sold as Walthers.

These pistols have serial numbers begining with the number "46", and were apparently made only in .40 S&W cal..

Mine has an O.D. frame, but I don't know if all of this varient do also.

Maybe someone can add more information to this "unusual" varient.