found this on Jans board dated 2012 with no responses
"The exact meaning of the PMP marking is still unknown but there is some speculation on its meaning Police Mecklenburg Pommern but no proof has yet surfaced to its validity".
now Im curious if its in world of lugers by Costanza
the p38 forum explains it as a PVP symbol but after seeing your pic it is PMP on that one as well
heres the link to that pic
http://www.p38guns.com/LugerPVP.htm