The lion was the Czech Army acceptance mark, and the "[19]23" is the date of acceptance, so the rifle is not wartime manufacture. It is a Vz 23, made for the Czech Army and the immediate predecessor of the better-known Vz (Vzor or Model) [19]24. About 130,000 Vz 23's were made, all but 10,000 in that year. The Vz 23 was superseded by the Vz 24 early in 1924, so its production life was short. The Vz 23 and Vz 24 are based on the standard German Model 1898 Mauser.
The Vz 23 was still in Czech service when the Germans took over Czechoslovakia in March, 1939, so many were captured and issued by the Germans to reserves and other rear echelon troops, with the standard K.98k being reserved for front line use. Many were captured by U.S. forces and brought back by returning GI's.
Jim