It's a Cobray M-11/9 which derived from the MAC-10. It's chambered for 9mm. The MAC-10 shoots .45.

From top to bottom on the sofa:
Romanian SAR-1 - 7.62x39mm
Mossberg 12 ga shotgun
Remington 700 .30-06
Ruger p90 - .45 acp
M-11/9