Hello,
to me this looks like an engraved "Edelweiß" (alpine flower) plus the letter "L" (in Latin handwriting). The "Edelweiß" was and still is the symbol of the "Gebirgsjägerdivision", but I doubt whether this was officially done by an armourer. It looks like an engraving which was done privately - maybe as a present to an officer.
By the way: this gun was made in 1941.
Dieter.