Help with proof marks

[cckling]

On a recently purchased luger, was told it was a 1920 commercial, I noted a scripted m on the barrel and on the receiver. On the underside of the barrel is the crown over n, serial number 1900, and the scripted m. On the receiver, serial number 1900, "GERMANY", and the scripted m. I cannot find the m on the proof page. Any ideas? Is my dating correct (1920)?

Thanx,