Question: The Ckm wz. 30 was a Polish-made clone of what American heavy machine gun used by the United States in World War I, World War II, Korea and to a limited extent in Vietnam?
Sentence (from "Ckm wz. 30"): Produced with various modifications such as greater caliber, longer barrel and adjustable sighting device, it was an improved although unlicensed copy of its predecessor, and was the standard machine gun of the Polish Army since 1931.
Relevant evidence: No