In the first half of the 1960s, as part of developments in the field of infantry automatic grenade launcher, the American company Honeywell was created one of the first heavy grenade launchers Mark 18 operating by turning the handle of the drive. However, the use of manual rotation schemes drive pen showed the inconvenience of its application: the shooter quickly get tired, there were disruptions crank mechanism, non-uniform flow of strongly deformed tape than it could do automatic feed of the tape cartridge.
In the mid-1960s to develop a new grenade to occupy the center of naval artillery (Naval Ordance Station) in Louisville, Kentucky. Before the developers was to create a new automatic grenade to arm Coast Guard boats and boats. New weapons being developed for shot 40h46 mm, followed in the M79 grenade launchers and mounted grenade launchers Mark 18.
In 1967, Honeywell Corporation was presented a prototype of the new grenade launcher Mk20 mod 0, and in 1968 the first batch of these weapons began to enter the army.
Grenade Mk 20 was the first fully automatic grenade launcher at 40h46 mm low speed flight. At the same time designers managed to maintain a low weight grenade launcher, making it more comfortable and not so bulky as Mark 18 grenade launcher.
grenade used scheme free shutter shooting with an unlocked gate. When the launcher is cocked, the barrel is moved forward, twisted barrel grenade launcher compresses the return spring when the spring is a compression of the barrel, the barrel moves it back, forcing him to run against grenade lodged by the energy of motion occurs nadkol capsule barrel grenade and takes the shot. Expense motion grenades forward rifled barrel grenade launcher barrel moves forward, thereby responding to reload the weapon. However, this method has allowed several offset the impact grenade that makes shooting more accurate.
Receiver grenade, made of a single sheet of metal having sufficient strength and relative ease.
Controls fire grenade Mark 20 are similar to those of the Browning M2HB machine gun and made a trigger on the handles.
shooting was carried out in a fully automatic mode, and single shots.
carried weapons such as fiberglass tape as in grenade Mark 18, capacitance 24 and 48 grenades. Submission tape performed as in Mark 18 grenade launcher on the left side, before it was required pre-load the first grenade into the chamber.
| Caliber, mm || 40h46 |
| Length mm || 685 |
| Barrel length, mm || 305 |
| Height, mm || 229 |
| Width || 175 |
| Weight (unloaded), kg || 9.7 |
| Feed count. Garnet || 24, 48 |
| Muzzle velocity grenades, m / s || 70 |
| maximum shooting distance, m || 400 |
Sights consisted of a folding rear sight open and flies.
grenade launcher could fire with a variable rate of fire from 250 to 275 rounds per minute and engage area targets at a distance up to 400 meters.
main user Mark 20 (Mk 20) became the U.S. Navy, a division of US Navy, River Rats. Grenade intended for the armament Coast Guard boats and boats, infantry machine installation, as well as armored vehicles. Also planned to create an infantry version grenade pistol grip, butt and bipod, but plans have not come true.
Grenade successfully used during the Vietnam War, where he showed the effectiveness of automatic grenade launchers, but also revealed the disadvantages of using grenades 40h46 mm from the M79 hand grenade to support weapons - insufficient firing range.
Total for 1971 was made in 1080 grenade when production was discontinued due to the adoption by the U.S. Army more effective grenade Mark 19, use a more powerful grenade 40x53 mm.