The EX 41 grenade launcher, also called the Shoulder-Fired Weapon (SFW), was a prototype multi-shot grenade launcher that was never adopted by the United States military. Most of its development was at Naval Ordnance Station, Louisville for the US Marine Corps in order to replace the single-shot M203. NOS Louisville had previously developed the Mk 19 and Mk 20 multi-shot grenade launchers. The Picatinny Arsenal also aided in the EX 41's development as part of the Army's Bursting Munitions Technology program. In its final form, the EX 41 was intended to weigh as little as 6.8 kg and have a range of up to 3,000 m. The program never progressed beyond concept models, but in November 1995, the design was sent to Knight's Armament Company for further development.
Instead of the standard low-velocity 40 x 46 mm grenade used by the M203 and M79 grenade launchers or the standard high-velocity 40 x 53 mm grenade used by the Mk 19, the EX 41 used a hybrid of the two developed by Indiana Ordnance. High-velocity ammunition such as the M430 HEDP and M918 practice grenades were fitted to the low-velocity cartridge cases, in order to have a longer effective range with a lower recoil. An optical sight of unknown manufacture was added to the top of the receiver to take advantage of the extended range of the ammunition.