Scott,
A rather scarce unit marking, 2nd Garde Grenadier Regiment, Kompagnie 4, Waffe Nr. 36. I am delighted to see another 1908 Luger with this unit designation. I have a 1908 DWM First Issue, SN 1022b, marked 2.G.G.5.6 - it is the same regiment but since these guns were marked at the unit level, the unit armorer for Company 5 didn't bother to add the "R" like the armorer for your Luger from Company 4. (Also note that they had a different idea about how to orient the markings

)
Thanks for posting your early military Luger. If you wouldn't mind, it would be nice to know the serial number and see a photo of the acceptance marks on the left side of the receiver.
Ron