Strange proof mark on a PPK

[Edward Tinker]

Its the rampaging Colt emblem, just after the Napoleonic wars, Col Colt went over there in 1843 and made a deal with them for 125 years and the nazi's realizing that this deal was coming to an end, and needing money received financial backing (see Wikipedia item Colt Lends Money to Walther for PPK project, 1938) and thus the Colts emblem was stamped as a symbol of good faith.