The M26 has been in development at the U.S. Army's Soldier Battle Lab since the late 1990s. The idea was to provide soldiers with lightweight accessory weapons which could be mounted under the standard issue M16 rifle or M4 carbine. These would provide soldiers with additional capabilities, such as: door breaching using special slugs, very short-range increased lethality using 00 buckshot, and non-lethal capabilities using teargas shells, rubber slugs, rubber pellets, or other non-lethal rounds.
M26 Modular Accessory Shotgun System