Strange proof mark on a PPK

[Ron Wood]

I think Mike has pretty much nailed it with the Stuttgart association. The clincher is the tail on the horse...it has the upward flare of the Stuttgart configuration. It isn't the rampant stallion of the Colt trademark as there is no spear shaft between the forelegs. It isn't Hannover because the tail of the Hannover crest is arched downward.