The Claymore mine is a directional anti-personnel mine developed for the United States Armed Forces, invented by Norman MacLeod. Unlike a conventional land mine, the Claymore may be command-detonated (fired by remote-control), and is directional, shooting a wide range of steel balls into a kill zone. The Claymore can also be activated by a booby-trap tripwire firing system for use in area denial operations.

The Claymore fires steel balls out to about within a 60° arc in front of the device. It is used primarily in ambushes and as an anti-infiltration device against enemy infantry. It is also used against unarmored vehicles.

Many countries have developed and used mines like the Claymore. Examples include models MON-50, MON-90, MON-100, and MON-200 introduced by the Soviet Union and used by its successor Russia, as well as MRUD (Serbia), MAPED F1 (France), and Mini MS-803 (South Africa).

Description

The M18A1 Claymore mine has a horizontally convex gray-green plastic case (inert training versions are light blue or green with a light blue band). The shape was developed through experimentation to deliver the optimum distribution of fragments at range. The case has the words "FRONT TOWARD ENEMY" embossed on the front of the mine. A simple open sight on the top surface allows for aiming the mine. Two pairs of scissor legs attached to the bottom support the mine and allow it to be aimed vertically. On both sides of the sight are fuse wells set at 45°.

Internally the mine contains a layer of C-4 explosive behind a matrix of about seven hundred steel balls set into an epoxy resin.

When the M18A1 is detonated, the explosion drives the matrix forward, out of the mine at a velocity of ,

The weapon and all its accessories are carried in an M7 bandolier ("Claymore bag"). The mine is detonated as enemy personnel enter the killing zone. Controlled detonation may be accomplished by use of either an electrical or non-electrical firing system. When mines are employed in the controlled role, they are treated as individual weapons and are reported in the unit fire plan. They are not reported as mines; however, the emplacing unit must ensure that the mines are removed, detonated, or turned over to a relieving unit. The M4 electric firing wire on a green plastic spool is provided in each bandolier. The M57 firing device (colloquially referred to as the "clacker") is included with each mine. An M40 circuit test set is packed in each case of six mines. When the mines are daisy-chained together, one firing device can detonate several mines.

The mine can be detonated by any mechanism that activates the blasting cap. There are field-expedient methods of detonating the mine by tripwire, or by a timer, but these are rarely used.

Development

The development of the M18A1 mine dates back to work done during World War II. The Misnay–Schardin effect was independently discovered during that war by József Misnay, a Hungarian, and Hubert Schardin, a German. When a sheet of explosive detonates in contact with a heavy backing surface (for example, a metal plate), the resulting blast is primarily directed away from the surface in a single direction. Schardin spent some time developing the discovery as a side-attack anti-tank weapon, but development was incomplete at the end of the war. Schardin also spent time researching a "trench mine" that used a directional fragmentation effect.

MacLeod applied for a patent for the mine on 18 January 1956, and was granted it in February 1961. The patent was later the subject of a civil court case between MacLeod, the Army, and Aerojet, which further developed the Claymore design. MacLeod's case collapsed when photographs of the German Trenchmine prototype were produced as evidence of prior art. It lacked the later version's iconic "FRONT TOWARD ENEMY" marking. The mine was planted in the ground, using its three sharp legs, and aimed in the direction of enemy approach; at that point, it was fitted with an electrical blasting cap. The mine was triggered from a safe position, preferably to the side and rear. The mine was barely more than a prototype and was not considered a "reliable casualty producer"; like the Phoenix it had an effective range of only . Given the requirements of weight and fragment density, approximately 700 fragments were needed, with the ability to aim the mine with an accuracy of around at the center of the target zone. The team at Aerojet were given access to all previous research into directional mines, including the M18 and the Phoenix, as well as German research. Dr. John Bledsoe led the initial project.

The original M18 mine fell far short of Picatinny's requirements. One of the first improvements was to replace the steel cubes with hardened 52100 alloy ball bearings. These performed poorly for two reasons. Firstly, the hardened steel balls spalled into fragments when hit by the shock of the explosion; the fragments were neither aerodynamic enough nor large enough to perform effectively. Secondly, the blast "leaked" between the balls, reducing their velocity.

International directional fragmentation AP mines

PADMINE is an anti-personnel directional fragmentation mine produced by the United Kingdom, similar to the Claymore in cosmetic design with two swivelling legs, inserted into soft-ground. Its lethality out to arrives in the form of 650 steel balls and it is activated by remote control or trip wire.

The M18 directional fragmentation anti-personnel mine, developed by Cardoen of Chile, contains 626 grams of explosives, surrounded by 607 anti-personnel fragmentation units providing a 60° arc of fire, with a lethal range.

Italy produces the DAF M6 and DAF M7 directional fragmentation mines, weighing respectively, with trip wire or remote control detonation. Their appearance is similar to the Claymore mine.

National copies

A number of licensed and unlicensed copies of the mine have been produced.

  • : C19 Defensive and Support Mine
  • : M18
  • : Type 66
  • : (Directional Charge) VP 88, "heavier" VP 84 and VP 2010
  • : IHR-60
  • : VS-DAFM 7
  • : P5 Mk1
  • : M18A2
  • : M18 Claymore
  • : MON-50
  • : M18A/M18A1
  • : MRUD (Mina Rasprskavajućeg Usmerenog Dejstva)
  • :
  • Shrapnel mine No 2
  • Mini MS 803 mine
  • :
  • K440, slightly smaller than the Claymore with 770 fragments.
  • KM18A1
  • :
  • FFV-013
  • Försvarsladdning 21
  • LI-12/Truppmina 12
  • : M18 AP Mine
  • : Arms Tech MM-1 "Minimore", a smaller variant conceived for Special Forces use
  • : MDH-C40. North Vietnamese copy during Vietnam War

Non-state actors

  • Viet Cong: Used homemade copies of Claymore mines.
  • Provisional IRA: used home-made variants in the Troubles. Dissident Irish Republicans have continued to develop them.

See also

  • List of individual weapons of the U.S. Armed Forces
  • Punt gun – similar killing effects at a wide area

References

Bibliography

  • International Coalition to Ban Landmines – Countries using Claymore type mines (PDF)
  • FM 23-23 ANTIPERSONNEL MINE M18A1 AND M18 (CLAYMORE) Field Manual—GlobalSecurity.org