NIB Beretta A400. Beretta A400 Xplor Unico Shotguns Beretta has unveiled the A400 Xplor Unico – a semiautomatic shotgun that features cutting-edge technologies and the world’s most advanced performance and engineering solutions all designed for exceptional performance. The Xplor underwent 3 years of development, 8,000 hours of engineering, 2,000 hours of testing and more than 100,000 rounds fired through prototypes and production models. The 3½” 12 gauge Beretta Xplor uses proprietary technology that enables it to shoot all types of 12 gauge shells with uncompromised performance, yet it weighs one pound less than other 3½” 12 gauge shotguns. The A400 Xplor is like a 3” semiautomatic that fires 3½” shells– and it is the cleanest, lightest, fastest and most versatile 12 gauge semiautomatic shotgun on the market today