This is a Kalashnikov USA AK known as the KS-12 chambered in 12 Gauge 3", model KS-12.
The KS-12 is a US manufactured 12 GA semi-automatic shotgun based on the Russian Saiga series. It is designed to accept 2.75" and 3" shells and includes a 5 round magazine. The KS-12 has a standard side mounted optics rail" a fixed buttstock and a standard pistol grip.
Features:
Accepts 2.75†and 3†Shells
Side Mounted Optics Rail
Fixed Buttstock