TacStar Sidesaddle, 12 Gauge, Fits Mossberg 500/590, Black 1081167 TacStar's new 4 round SideSaddle Shotshell Carrier is the perfect accessory for all your hunting shotguns. The 4 round SideSaddle mounts easily to the side of the receiver and requires no modifications to the shotgun. Each SideSaddle is designed to provide clearance for long forends and come with all mounting hardware. SideSaddles keep extra shells securely in place and in the perfect location for reloading. No more digging in your pockets for extra shotgun shells.