What kind of magazine is that?
Helical magazines extend the drum magazine design so that rounds follow a spiral path around an auger-shaped rotating follower or drive member, allowing for large ammunition capacity in a magazine that can be adapted to increase ammo capacity with only a minor increase to the dimensions of an unloaded gun. This type of magazine is used by the Calico M960, Bizon SMG, Long Wind CS/LS06 and KBP PP90M1.