Hoyt,
Your brother's Luger served in WWI in a medical unit of a logistics support column. B.1.T.S.3.327. would be "Bayerisches, 1 Train-Bataillon, Sanit�¤ts-Kompagnie 3, Waffe Nr. 327"; translates as Bavarian, First Train Battalion, Third Medical Company, weapon #327.
There is a post in Jan Still's Forum,
http://luger.gunboards.com/topic.asp...Terms=bavarian, which profiles another Luger marked to such a battallion, along with a list of your brother's gun's unit-mates.
If you can, please find out all the pertinent gun identification--make, serial number, year if present, holdpoen if present, etc., to be able to add to the list. Pictures would be great to see.
Please tell your brother that he has a very cool Luger, and we are glad to know about it.
Also, I'm sure that Ed Tinker would like to know the story of this gun's capture (as would we all).
--Dwight