Which American manufactured submachine gun was informally known by the American soldiers that used it as "Grease Gun"?

The story behind the answer

M3 is correct. The U.S. M3 submachine gun earned the nickname “Grease Gun” because its stamped sheet‑metal, tubular shape closely resembled the hand-operated grease guns used by mechanics. Introduced in 1943 to replace the heavier, expensive Thompson, the M3 fired .45 ACP, had a slower, more controllable rate of fire, and