The XM148 was an experimental 40 mm grenade launcher developed by Colt Firearms as the CGL-4 (Colt Grenade Launcher). Colt manufactured the launcher for field testing during the Vietnam era. After problems with the experimental design were discovered, the XM148 was replaced by AAI Corporation's conceptually similar M203 design, which became the primary grenade launcher used by the US armed forces and others until its ongoing replacement with the M320.