Beretta A400 Action, Semi Automatic, 20 Gauge, 3 Chamber, 28 Barrel Steelium Barrel, Bronze Receiver, Micro Core Recoil Pad, Optima Choke, Walnut Wood Stock, 2 Rounds J40AA28 The A400 is a gas-operated action that was built for speed, reliability and versatility. The A400 action is self-cleaning, so it requires much less maintenance than any other shotgun you'll ever own. When you take this gun apart you'll be amazed by the intuitive simplicity of the tool-free field-stripping process and by what little maintenance the A400 requires.