Mr. Orv Reichert seems to be the first person to mention it. Upon comments made by an Australian friend that either was doing it or knew that people were.Not saying I recommend it, but I have read on a number of different Walther forums that .380 will function just fine in the 9x18 PP Super.
First off the bat, I would recommend .38 Super Comp brass. Starline manufactures it. It will last you a lifetime, made much stronger than what's required for the 9x18U specs. Need to trim it. The 9x18 Makarov tool for measuring case length will do just fine.I have been thinking of loading my own but getting the brass and tooling is just as difficult it seems. I would be intrested in what others are using to reload and a source for brass.