Mk 2 grenade

The Mk 2 defensive hand grenade is a fragmentation

Fragmentation (weaponry)

Fragmentation is the process by which the casing of an artillery shell, bomb, grenade, etc. is shattered by the detonating high explosive filling. The correct technical terminology for these casing pieces is fragments , although shards or splinters can be used for non-preformed fragments...

 hand grenade (sometimes written Mk II) used by the U.S. armed forces

Military of the United States

The United States Armed Forces are the military forces of the United States. They consist of the Army, Navy, Marine Corps, Air Force, and Coast Guard.The United States has a strong tradition of civilian control of the military...

 during World War II

World War II

World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

 and in later conflicts including the Vietnam War

Vietnam War

The Vietnam War was a Cold War-era military conflict that occurred in Vietnam, Laos, and Cambodia from 1 November 1955 to the fall of Saigon on 30 April 1975. This war followed the First Indochina War and was fought between North Vietnam, supported by its communist allies, and the government of...

. The Mk II was standardized in 1920 replacing the Mk I

Mk 1 grenade

The Mk 1 grenade is a fragmentation hand grenade used by American forces during World War I. According to its designers, it was to be the "simplest", yet most "fool-proof", grenade ever made...

 of 1917. It was phased out gradually, the U.S. Navy

United States Navy

The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...

 being the last users. It was replaced by the M26-series and later M61

M61 grenade

-Description:The M26 is a fragmentation grenade developed by the United States military. Its distinct lemon shape led it to being nicknamed the "lemon grenade"....

 and M67 grenade

M67 grenade

The M67 grenade is a fragmentation hand grenade used by the United States Military and Canadian Forces, where it is referred to as the C13. The M67 is a replacement for the M61 grenade used during Vietnam and the older Mk 2 "pineapple" grenade used since World War II.-Composition:The M67 Grenade...

s. On 2 April 1945 the Mk II and Mk IIA1 were redesignated the Mk 2 and Mk 2A1.

Description

The Mk 2 was commonly known as a "pineapple" grenade, because of its shape and structure. Grooves were cast into the cast iron

Cast iron

Cast iron is derived from pig iron, and while it usually refers to gray iron, it also identifies a large group of ferrous alloys which solidify with a eutectic. The color of a fractured surface can be used to identify an alloy. White cast iron is named after its white surface when fractured, due...

 shell, which was believed at the time to aid in fragmentation and had the side benefit of aiding in gripping the grenade—this provision gave it the appearance of a pineapple

Pineapple

Pineapple is the common name for a tropical plant and its edible fruit, which is actually a multiple fruit consisting of coalesced berries. It was given the name pineapple due to its resemblance to a pine cone. The pineapple is by far the most economically important plant in the Bromeliaceae...

 fruit. Although TNT was used as a filling, EC blank fire (smokeless

Smokeless powder

Smokeless powder is the name given to a number of propellants used in firearms and artillery which produce negligible smoke when fired, unlike the older gunpowder which they replaced...

 firearm) powder was also used instead in some models due to the tendency of TNT to over-fragment the cast iron body. EC powder produced an adequate amount of fragmentation and did away with the need of a detonator. The detonator was initially replaced by a small length of safety fuse terminated with a black powder

Gunpowder

Gunpowder, also known since in the late 19th century as black powder, was the first chemical explosive and the only one known until the mid 1800s. It is a mixture of sulfur, charcoal, and potassium nitrate - with the sulfur and charcoal acting as fuels, while the saltpeter works as an oxidizer...

igniter charge. Production grenades with the EC powder filler used the M10 series of igniting fuse. It was also commonly referred to as a "frag" grenade. The Mk IIA1 was introduced in 1942 and lacked the bottom filler hole of the Mk II being filled through the fuse well. The Mk II was identified with an all yellow body prior to 1943. They were then painted olive drab for camouflage purposes with a narrow yellow band below the fuse. Repainted yellow grenades usually lacked the yellow band.

Variants

• Grenade, Hand, Fragmentation, Mk II: EC blank powder filler, uses M11 or M10A1 igniting fuse.
• Grenade, Hand, Fragmentation, Mk IIA1: EC blank powder filler, uses M10A2 igniting fuse.
• Grenade, Hand, Fragmentation, HE, Mk II: TNT filler, uses M5 detonating fuse.
• Grenade, Hand, TNT, Fragmentation, Mk II: TNT filler, uses M6A4C detonating fuse.

Specifications

• Fuse: Dependent on variant, includes M5 and M6 detonating fuses, and M10 igniting fuses. Later model fuses could also be fitted.

External links

• Information about the Mk 2 at inert-ord.org
• Film of detonating Mk2 grenade — 2/3 million frames per second