This blowback action SMG does fire from the open bolt just like the M3 firearms did. Noteworthy features include the collapsible wire stock, drop-free 60 round magazine, fixed peep style sights, and a 1,050 BB per minute rate of fire. Like other Legends SMGs, the M3 Grease Gun is powered by (2) 12-gram CO2 cartridges. Expect to shoot approximately 120 BBs (three magazines) for each full Co2 charge.