A mobile scanner gun system efficiently and reliably processes a retail store purchase and/or performs daily store inventory management functions. The system has a main body portion extending toward a handle portion, the main body portion having a base, side walls, a front wall and a back wall constructed to form an interior cavity, wherein the front wall includes an aperture with a lens recessed therein. The front wall has a trigger member located near the base of the main body. A USB MSR input device integrated on the short edge of the mobile tablet device (upper receiver) is used for processing payment card sales transactions through a secured PCI compliant, end to end encrypted bank card processor. The mobile tablet device has a system integrated therein that enables real-time store level inventory management and fully functioning POS capability for selling merchandise in a retail sales environment.