The Calico M960 is a roller-delayed blowback submachine gun-class weapon marketed primarily to military, security and law enforcement elements by Calico Light Weapon Systems (CLWS). A semi-automatic-only civilian model known as the "Liberty" has also been developed. CLWS was originally based out of Oregon after being founded in 1982 as a private concern to which it then moved operations to Nevada before returning and settling in Hillsboro, Oregon. Calico is best known for its line of .22 rifles, 9mm pistols, M900 series carbines and M750/M900 series submachine guns (including the M960/Liberty).
The Calico M960 series has yet to secure any large-scale quantitative defense contracts though it remains an intriguing design endeavor. It sports features uncommon to most assault weapons in current use worldwide as it manages a small working profile with less protrusions that are likely to snag in the heat of battle. It is also a well-balanced design in the hands. Calico weapons are noted for their reliability and accuracy as well as robust function and long life.
The Calico M960 series is unique in its general design in that it makes use of a helical-feed magazine, a cylindrical drum fitted over the rear portion of the receiver and adjustable shoulder stock. The primary benefit of this arrangement lies in a larger internal magazine that can hold up to 100 rounds of ammunition where traditional submachine guns are generally limited to 20-, 30- or 40-round detachable box magazines. The weapon is chambered to fire the widely-accepted 9x19mm Parabellum pistol round from a 50- or 100-round drum at a rate of 750 rounds per minute with spent shell casings ejected through the bottom of the receiver, ahead of the trigger guard (thusly making it ambidextrous). Iron sights are standard though optics can be fitted as necessary. The rest of the design consists of a conventional angled pistol grip with integrated trigger unit, a handguard with angled foregrip and a protruding barrel assembly capped by a perforated muzzle brake. Overall weight is 2.17 kilograms when empty and the stock can be collapsed to form a 647mm overall length (down from the full 835mm extended length). Overall construction includes metal for the critical internal working components and lightweight composites for the furniture.
The basic production mark of the weapon line became the M960A with its collapsible stock and this was followed by the compact, selective-fire M961A with its shorter barrel. The M960AS was given a fixed stock. As mentioned, Calico also markets the M960 family under the "Liberty" name and the product line encompasses the Liberty 50, Liberty 50 Tactical, Liberty 100, Liberty 100 Tactical, Liberty I, Liberty I Tactical, Liberty II, Liberty II Tactical, Liberty III and Liberty III Tactical. Each is differentiated by obvious physical changes (fixed/collapsible stock) to the base design to suit the discerning customer. Law enforcement and military versions are offered with full-automatic fire functionality whilst civilian-minded designs are limited to semi-automatic fire only. The "Liberty III" series takes on more of a "machine pistol" form and is lighter in overall weight and made more compact thanks to its lack of a shoulder stock and shortened barrel assembly. "Tactical" models incorporate Picatinny-style rails for additional tactical accessories mounting. All models range out effectively to 300 yards maximum according to Calico marketing materials.