The Browning Automatic-5 or simply Auto-5 or A-5 is a recoil-operated semi-automatic shotgun designed by John Browning. It was the first successful semi-automatic shotgun design, and remained in production until 1998.
It was the first mass-produced semi-automatic shotgun. Designed in 1898 and patented in 1900, it was produced continually for almost 100 years by several makers with production ending in 1998. It features a distinctive high rear end, earning it the nickname "Humpback". The top of the action goes straight back on a level with the barrel before cutting down sharply towards the buttstock. This distinctive feature makes it easy to identify A-5s from a distance. A-5s were produced in a variety of gauges, with 12 and 20 predominating; 16 gauge (not produced between 1976 and 1987) models were also available. The shotgun saw military service worldwide from World War I through the Vietnam War. The weapon was used heavily by members of the Special Air Service in the Malayan Emergency, who found the semi-automatic shotgun perfect for close quarter jungle fighting.
