Armatac makes a dual drum magazine. At first glance one might think of a Beta C-Mag. However, that is as far as the similarities lie. The Armatac drum holds 150 rounds of 5.56. It is compatible with .300 blackout. The length of the ammo is crucial. 2.260 is the maximum length the ammo can be otherwise it will cause the drum to malfunction. Due to the method that the drum feeds ammo, it can work with full-length blanks. According to the representative, the Armatac drum does not need any form of lubrication like other drums.
The drum retails for $420.