Ordnance Notes -- by Bob Stoner GMCM (SW) Ret.

M79 40mm Grenade Launcher

The M79 grenade launcher was a very handy firearm as shown in the hands of a Navy PRB crewman during the Viet Nam War. The M79 had a very simple break-open action. (Photo: US Navy)

The M79 is a break-action, single-shot, air-cooled, 40mm grenade launcher. It is a shoulder weapon designed to bridge the gap between the infantry's thrown hand grenade and supporting mortars (50 to 330 meters). The M79 entered service with the US Army in 1961. The new grenade launcher replaced the rifle grenade which had filled this hand grenade-to-mortar range gap since the middle of World War 1.

The M79 grenade launcher was a very simple arm. Because the grenade's trajectory was so high, the M79 was easily recognized by this long folding leaf sight, short barrel, and distinctive-shaped stock. The leaf rear sight is shown folded forward in the photo. A spring-loaded plunger at the front of the trigger guard would allow it to hinge to either side. This gave access to the trigger when soldiers were using thick gloves in cold weather. The latch lever that allows the barrel to hinge down for loading is directly behind the hump at the end of the barrel where the top of the stock joins the breech face. The M79 recoil was mild – even through the thick rubber butt pad suggests differently. The launcher would set itself to SAFE whenever the breech was opened. To FIRE, the operator pushed the sliding safety (directly behind the latch lever) forward. (Photo: U.S. Army)

Early 40mm HE grenades could arm in as little as 5 meters (16.5 feet). This was found to give insufficient protection for jungle fighting. A later 40mm HE grenade extended the arming distance to 15 meters (45 feet). Muzzle velocity of the grenade is 75 meters per second (246 feet per second). The HE grenade has a kill radius of 5 meters (45 feet) and a wounding radius of 15 meters (50 feet). The HE grenade contains approximately 300 fragments.

Ammunition for the M79 is high explosive (HE), high explosive-dual purpose (HEDP), target practice (TP), riot gas (CS), APERS (flechette or 00 buckshot), smoke streamers, star clusters, and parachute flares.

The M79 has been replaced by the M203 launcher that attaches to the M16 rifle or M4 carbine in SEAL teams. Although obsolescent, the M79 may still be found in Naval Special Warfare armories.

M79 40mm GRENADE LAUNCHER TECHNICAL DATA:
Caliber – 40x46mmSR
Length -- 29 inches
Weight -- 6.6 pounds
Barrel length -- 14 inches
Maximum range -- 400 meters (440 yards).

© 2009 Bob Stoner R5