Calico M950

The Calico M950 is a pistol manufactured by Calico Light Weapons Systems in the United States. Its main feature, along with all the other guns of the Calico system, is to feed from a proprietary helical magazine mounted on top, available in 50 or 100-rounds capacity.
The factory sights enable reasonable accuracy to about 60 meters (197 feet), but 100 meters is a reasonable range.
The .22 LR weapons use a separate design than the 9mm offerings, and share no parts with their larger siblings.