Markings questions for DWM 1921?
 

What is this marking for the top of my barrel?
DWM192 sn: 87191
Also one more question, is this side plate number correct for my gun?
thanks, Bob

It is the power-proof stamp, the same e/ArA 4 which is the rightmost stamp on the right receiver. It is just very lightly stamped.

--Dwight

Bob,
I think that the number on the inside of the sideplate is a worker/inspectors mark. You can also find various numbers and letters in hidden places on the frame, receiver, and toggles.
They were applied at different times during production. The numbers on Mauser sideplates relate to the serial number.