Claymore

The M18A1 Anti-Personnel Mine, frequently referred to as the Claymore is an Anti-Personnel Mine used by the United States military. It was named after a large Scottish sword by its inventor, Norman A. MacLeod. It features in both the single player and multiplayer in Call of Duty 4: Modern Warfare. In the multiplayer, it is unlocked at level 23.

Description
The M18A1 consists of a horizontal, convex olive-green plastic case holding 700 steel ball bearings in front of a block of Composition 4 explosive set into an epoxy resin. On the front of the mine, the words "FRONT TOWARDS ENEMY" are printed, whereas the simple word "BACK" is located on the rear of the mine. The mine can be propped on a pair of scissor legs, allowing it to be detonated vertically.

The Mine can be operated as an ambush or defensive device. It can be detonated with the use of an M57 "Clacker" detonator or through infrared sensors, tripwires and timed fuses.

When detonated, the mine releases the 700 balls, breaking them from their resin wall and creating a 60 degree spread that is 2 meters high with a range of 50 meters. The force of the explosion deforms the steel balls into a shape roughly similar to a .22 Rimfire bullet. The mine is devastating against infantry, though it can be effective against softly armored vehicular targets as well.

History
The Mine can trace its origins to WWII, from the discovery of the Misznay-Schardin Effect. Named after Misznay, a Hungarian and Dr. Hubert Schardin, they discovered that when a solid metal plate is placed behind an explosive, the force of detonation is pushed away from the metal plate to a single direction. They originally applied the design to a prototype for an anti-tank weapon, but the war ended before production could begin.

Later, during the Korean War, U.N forces faced Chinese infantry waves, often numbering in the hundreds. With no official weapon capable of fighting such human waves, it was a serious threat during any combat engagement. In 1952, MacLeod's design was introduced to the U.S military, though it was not until 1961 when several were exported to Vietnam that it saw any service and only until the improved M18A1 was issued did it become a significant weapon.

Since that time, the mine has been produced in a variety of versions by the United States army as well as many licensed and unlicensed reproductions. One in particular, the MON-50, is a near carbon-copy of the M18 produced by the former Soviet Union.

While the weapon is considered an anti-personnel mine, it does not specifically violate The U.N Mine Ban Treaty. The "Controlled" Versions, using a "Clacker" detonator do not violate the treaty, whereas the use of "Tripwire" mode Claymores do violate the treaty. To this end, the United States Military only uses the "Controlled" mode.

Call of Duty 4: Modern Warfare
The Claymore is used in both the Single and Multiplayer modes. In single player, the Claymore can be used to prepare an area for enemy assault or to cover a vulnerable flank, as it only causes damage directly in front of the mine as opposed to a bubble-effect like grenades or C4.

In single player, claymores will usually be in your inventory at the start of the level, and you will often start with 2 of them. Many players will rarely use them as they have no real tactical purpose except in One Shot, One Kill. The only claymore preset in the game is in One Shot, One Kill. After sniping Zakhev, look to the left before roping down. There is a claymore in front of the door (in case an enemy came upstairs to ambush the sniper team).

In multiplayer, the Claymore is unlocked at level 23 and can be used to defend a position from enemy assault. This is mostly used by snipers who want to defend their position from an enemy bent on killing them. You are given only two at a time, however, as a perk in your first slot; thus, other possible choices such as an RPG-7 or extra Special Grenades are forfeited. You can also increase the amount of damage delivered by the claymore by using it with the Sonic Boom perk, which increases the damage of all your explosive weapons. When activated, the Claymore will make a single clicking sound, before detonating (.83s delay). A Claymore can be spotted by the red lasers it produces or with the Bomb Squad perk. Defeating a Claymore can be done by throwing a grenade at its position or shooting the mine. Although not harmful to the person setting it down when detonated if said person is standing behind it, it will kill or seriously injure a player if it is detonated with them in front of it. A skilled player can defeat an enemy in this way. It is often met with very annoyed responses by players.

Call of Duty: Modern Warfare 2
The Claymore returns in Call of Duty: Modern Warfare 2, but this time it is in the Equipment slot instead of being given via a perk. Also, you only get one instead of two. Unfortunately it is far weaker and slower, taking several second to activate once tripped and seems to rarely kill enemies. A skilled enemy can hear it tripped as soon as if is first flipped and back off just before it explodes.