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. It was designed for installation below the barrel of M16-type rifles, and was intended to replace the stand-alone M79 correcting the problem of grenadiers relying on pistols as a secondary weapon. After problems with the experimental design were discovered, the XM148 was replaced by AAI Corporation's conceptually similar M203 design, currently the primary grenade launcher used by the US armed forces and others today. Originally made for use with the M16 Rifle, the XM148 was also used by US Special Forces in conjunction with the XM177E2 and the Australian SASR in conjunction with the modified L1A1, nick