Beta C-Mag

The Beta C-Mag is a 100-round capacity magazine manufactured by the Beta Company. It was designed by Jim Sullivan and has been adapted for use in numerous firearms firing the 5.56×45mm NATO, 7.62×51mm NATO, and 9×19mm Parabellum cartridges. C-Mag is short for century magazine, referring to its hundred-round capacity. It has two drum units, each of which hold half of the cartridges inserted into the magazine. The latest version of the magazine is available with a transparent backing to allow the user to see the number of rounds remaining in the magazine. A C-Mag loaded with 5.56×45mm NATO ammunition typically weighs about 2.1 kg (4.63 lb); a C-Mag loaded with 7.62×51mm NATO ammunition weighs 4.77 kg (10.5 lb).

One such magazine has been designed for the M16 rifle, in use by the US Military. The NATO Stock Number for the M16 version is 1005-01-363-6670. The magazine design, including drawings, is covered in detail in U.S. Patent 4,658,700.