LugerForum Discussion Forums - 1916 DWM Luger with unknown unit markings

1916 DWM P08 Luger
I purchased this Luger 12/24/16 from my wife's uncle Dale. He would stop by a pawn shop on the way home from school several times during the week in Elberton, Ga. One day in 1955 he found this 1916 Luger and a long barreled Artilley Luger. He asked his dad to go with him to purchase it and he left with the Luger, 1917 dated holster, tool, and two magazines and $25 less in his account. He shot it a few times after that, and in 1970 he and his wife took a firearms course in Cobb County, Ga and used this Luger. The instructor told him it was the most accurate gun in the class. After that he stored it away in the holster, tool, and both magazines loaded, never to be shot again. Around 1996 he put it in his banks safety deposit box, again stored in the holster with the tool and two mags loaded with 8 rounds each. He emailed me about 3-4 weeks before Christmas saying he knew I collected guns and would I be interested in this one. I collect old S&W revolvers but have been wanting a nice Luger for awhile. I, of course, said I would be interested. He nor I knew much about them. He asked me to post some pics on some forums and see what the value was. I also sent him pages of completed auctions on Gunbrokers. Some forum members were able to help me with a ballpark figure and and I passed on their stated value and input to him. We meet on Christmas Eve at a family get together and after looking it over I made him an offer that I felt was fair, and an offer that he apparently felt was fair, as he was a little shocked. He said he was more than happy with the price and I was too. After my research I've found that it is a 1916 DWM Luger, with what appears to be the correct markings on the right side of receiver. Numbers are all matching (per chart showing which parts are marked), including grips (but not magazines), several of the numbers appear to have the correct "halos" that go along with an original finish, and all edges and lettering appear to be sharp. The serial number is 4691 M, and it has unit markings on the front grip frame as follows- 2.M.C or possibly G. R.158. I've pictured the tool and an up close pic of the markings but I can't tell what the marking is. The gun, holster (dated 1917) tool and magazines are all as they were since 1955. It's unknown if the tool or holster is original to the gun before that time. It appears one mag is WWI era, but the wood is broken on one side, and the other from WWII. Is this correct?
Are the holster and tool both correct for this gun?
Would this gun have been a unit from WWI or II?
Would it have been used during WWII?
Would a 1917 holster been issued with this gun?
If anyone could help with the year made (1916?) and what the unit markings mean that would be appreciated. My wife's uncle was very happy to hear that it would stay in the family and since it's all matching it will probably remain unfired since 1970. I'm shocked it's in the condition that it is in (90%+) since it's been stored in the holster at least since 1955 along the the tool. But the tool with now be stored in a small plastic baggie, and the holster also in a plastic baggie. Any help on these questions would be appreciated.
Thanks!
Jeff