The MARS (Mini Assault Rifle System) was an experimental, scaled-down variant of the M16 rifle tested by Colt as a personal defense weapon (PDW) in the 1990s. It was chambered for the experimental 5.56x30mm MARS cartridge. The 5.56x30mm cartridge fired a 55 grain projectile at 790 m/s (2,591.9ft/s). The rifle was patented in 1998 (US patent no. 5,827,992).