I have an antique silver tankard with 24 medallions attached from Johann Karl Hedlinger's Regents of Sweden series. The top of the lid has medallions of Swedish royalty from the 1600's. There is a hallmark stamped on the bottom which depicts a "G" with a crown. This could possibly mean Gothenburg. Sweden? Next to that is possibly a makers mark "SM" and then another hallmark to the other side. I am having difficulty finding information on this hallmark. If you could provide any insight it would be greatly appreciated! I am not sure if this is a low grade silver hallmark or if the piece is merely plated. This is the only hallmark I could find on the piece.
Please see photos.
Please note that the hallmark images have been flipped and the "G" with a crown is upside down when the tankard is sitting upright. This may help with the orientation of the other hallmarks.
Thank you for your time.

