This is a slightly larger version of the M950. It has a sliding stock and a forward grip to aid in controlling the weapon. It has a muzzle compensator to control the rise and it can accept the same round helical drums as the M950.
—Omega Strain Equipment Screen Description
Included in Omega Strain as the Helico 960, the Calico M-960AS is an enlarged Submachine Gun version of the Calico M-950. Having a stock, a muzzle compensator and a frontal hand grip combined with the large 50-round magazine makes this weapon very effective at both close and long ranges in addition, it is very controllable and can be easily used in first person mode to be accurately fired in full automatic.
Primarily included in the Murakawa Tower mission in Tokyo, Japan, this weapon is used by certain Yakuza officers and Murakawa Tower Security Personnel and can be also captured from certain enemy weapon crates.
Unlike it's equipment screen description (which would point to a different Calico M-960A variant), this specific Calico M-960 version haves a solid stock instead of the mentioned sliding stock.