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 "M1917 Browning machine gun"): There were two main iterations of it: the M1917, which was used in World War I; and the M1917A1; which was used thereafter.
Relevant evidence: No