The Calico M-900S Carbine is part of a complete weapon system that contains pistols, submachine guns, and carbines, all of which operate upon the same principles. They are unusual weapons, principally because of their magazine system, which allows a very large capacity magazine to fit into a compact space.
The company began by developing a helical-feed magazine for a .22 rifle in 1985. They then produced improved versions to accept 9 mm parabellum cartridges, and from this went on to develop a number of different weapons in this caliber which has been adopted by several military and security forces around the world.
The helical magazine is a plastic molding only 57 mm in diameter. Using a staggered helix principle, the rounds are driven forward along with a fluted cartridge carrier as they press against the helical walls of the magazine. The driving pressure is provided by a torsion spring. The cartridges are fed one by one to a feed port, from where they are guided into the top-loading chamber of the weapon. Loading the magazine is easily done, and a 50-round magazine can be loaded in 22 seconds.
The receiver is of cast aluminum, with steel inserts in areas subject to wear. The breech is closed by a roller-locked bolt of similar design to that used in the Heckler & Koch and CETME assault rifles and submachine guns, which allows the weapon to fire from a closed bolt and delays bolt opening long enough for the bullet to leave the muzzle, and the chamber pressure to drop to a safe level. The ejection of the spent case is downward, in front of the trigger guard, and it is possible to fit a cloth ‘brass catcher’ to collect the fired cases.
In spite of the long barrel, the 178 mm sight base is relatively short, the rear sight forms part of the magazine and the foresight is mounted an elevated base at the front end of the magazine. The rear sight flips between a notch and an aperture, and the front sight is adjustable for elevation and windage.
The Calico M-900S’s 100-round magazine fits in exactly the same place as the 50-round, but extends back over the stock; it also adds 1.69 lbs (0.77 kg) to the weight of the loaded weapon.
Technical specifications: Calico M-900S Carbine
|Manufacturer:||Calico Inc., Bakersfield, CA, United States|
|Type:||delayed blowback, semi-automatic|
|Caliber:||9 mm Parabellum|
|Barrel:||16.1 in (409 mm)|
|Weight (empty):||7.06 lbs (2.87 kg), loaded with a 50-round magazine|
|Magazine capacity:||50 or 100 rounds|