So from the current Merkel O/U thread,

"According to the book, involvement in the firearms trade for his family began with Friedrich Ernst Ferdinand Merkel(1821-1901), an engraver, and continued by Ernst August Merkel(1853-1912) and by his son Louis Ferdinand(1866-1904). The Merkels became well established gunmakers in Suhl. Bernhard Emil Merkel(1874-1954), son of Friedrich Ernst Ferdinand, founded his own business around the turn of the century(20th), to be followed by his son Fritz(1906-1976).",

the "GEM" might be stamp initials of Gebhardt Emil/Ernst Merkel. Either he was a cousin to the Merkels or one of the above had 4 names and Gebhardt was in the mix somewhere.

Kind Regards,

Raimey
rse