Hi Luke, if you look carefully, there is a nonsymmetry between the right and left sides of the top cross. Could it possibly be a heavy strike and consequent wear of the letter "r"?? According to Jan Still (Page 15 Imperial Lugers) 1917 and 1918, both Erfurt and DWM produced pistols at least into the R-Block and some higher. My guess, since it doesn't have the Erfurt stamp, is that it's a DWM.