This is a discussion on When was HK psp made within the Defensive Carry Guns forums, part of the Defensive Carry Discussions category; serial 14xxx and says DE...
"In a world of compromise, some men don't." HK ad slogan from the 1980's.
There is a 2 letter sequence on the pistol that is the date code that is on the frame by the proof mark which is the eagle over N if I remember correctly being the location
A B C D E F G H I K
0 1 2 3 4 5 6 7 8 9
If your pistol does not have an actual date or date code, (some don't), then the serial number indicates a very early production, probably 1980 or 1981.
The DE is just a required stamp indicating the gun shipped from Germany. All guns now made there have the DE stamp.
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General Robert E. Lee