stamp on barrel of 1894 CL

[Scotty]

While mounting a scope on my 1894 CL, I noticed what I thought was a rust bubble or a ding or something on the left side of the barrel about a 1/2 inch from where the barrel enters the receiver. I got a magnifying glass and could see that it is a stamp "JM" . Can anyone tell me what that is there for and why? It does nothing for the appearance of the rifle. I thought maybe it is a inspection stamp. Scotty