Slumlord,
Erfurt Lugers are fascinating because of the markings which are found all over them. Rather than repeat much of what has already been posted various places on this Forum, please click
This Link to see a profile of a 1911 Erfurt which discusses much of what you want to know about Erfurt Lugers. You can also do a search on "Erfurt" which will tell you lots more.
In 1914 Erfurt manufactured approximately 23,000 LP-08 (Artillery model, 8" barrel) but only 7,000 standard 4" barrel pistols. This makes it the rarest of the standard Imperial German Army Lugers.
I definitely want to see more, sharp, closeup pictures of your friend's noteworthy Luger, and I'm sure I'm not alone.
--Dwight