721 bolt face markings

[arturo1113]

Ive owned 4 different 721s and a 3 722s but I just purchased a 721 made in January of 1950. The bolt face is marked with the caliber, 30 06, and JMD- (there is one more letter but cant make it out). On the others Ive owned I never saw a bolt face marked with the caliber. Did they do this with the early guns or is this an anomoly. Yours Art Koscielski