Another Walther question

I noticed in a list of Walther parts, that the firing pin for the Walther PP and PPK can be either round or flat. About when was a change made and are the firing pins for the PP and PPK the same length? Any help is greatly appreciated.

I believe the change was made beginning with the new post-war guns. Up until 1945 the pin was flat, after the war, Walther did a slight re-design of the P-38 and the PP series.

The PP's pin was changed at that time.

Thanks for the help.:)