In 1939 Germany occupied Czechoslovakia and by early 1941 all production was diverted to the German war effort. In early 1940, the Germans changed the slide top markings to BOHMISCHE(German for Czechoslovakia) WAFFENFABRIK A.G.PRAG followed by Waffenamt stamp and Serial Number. Your slide does not have stamp or serial number on slide top so it was probably replaced later in the war. When the slide top markings were changed so were the left side slide markings. Early 1940 changed to Pistole Modell 27 Kal 7.65. In June 1943, the side markings were changed to add German Code for the location of factory where produced and added the code fnh to the left side of slide before Pistole. Looks like your CZ vz27 was produced early 1940 to mid 1943. Without seeing the serial number, this is the best I can do. Want to sell it?