M6 aircrew survival weapon
The M6 aircrew survival weapon was a specially-made .22 Hornet over .410 bore combination gun issued to United States Air Force aircrews to help forage for food in the event of a plane crash. It was issued from 1952 until the early 1970s, in conjunction with the M4 Survival Rifle.
Source: Wikipedia — M6 aircrew survival weapon (CC BY-SA 4.0)