The Browning Automatic 5, most often Auto-5 or simply 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.
The name of the shotgun designates that it is an autoloader with a capacity of five rounds, four in the magazine and one in the chamber.
The Remington Model 11 was the first semiautomatic shotgun produced in the United States.
After the Remington 1100, the Browning A-5 became the second-best-selling auto-loading shotgun in U.S. history.
Here’s an animation of the cycling operation of this awesome shotgun. This gives you a different perspective of how it all works on the inside.
Sources: Si vis pacem Youtube, Wikipedia