M18A1 Claymore mine

Description
The M18A1 Claymore mine consists of a horizontally convex olive green plastic case (inert training versions are blue), which is vertically concave. The shape was developed through experimentation to deliver the optimum distribution of fragments at 50 meters (55 yards) range. The case has the words "Front Toward Enemy" embossed on the front surface of the mine. A simple open sight is provided for aiming the mine on the top surface. Two pairs of scissor legs attached to the bottom support the mine and allow it to be aimed vertically. Either side of the sight are fuse wells set at 45 degrees to the vertical. Internally the mine contains a layer of C-4 explosive on top of which is a matrix of approximately seven hundred 1/8 inch diameter steel balls (about as big as #4 birdshot) set into an epoxy resin.

When the M18A1 is detonated, the explosion drives the matrix of 700 spherical fragments out of the mine at a velocity of 3995 feet per second (1,200 m/s) [1], at the same time breaking the matrix into individual fragments. The spherical steel balls are projected in a 60° fan-shaped pattern that is two meters high (6 ft, 8 in) and 50 meters (165 ft) wide at a range of 50 meters (165 ft). The force of the explosion deforms the relatively soft steel fragments into a shape similar to a .22 rimfire projectile [1]. These fragments are moderately effective up to a range of 100 meters (328 ft), with a hit probability of around 10% on a prone man-sized 1.3-square-foot (0.12 m2) target (0.12 square meters). The fragments can travel up to 250 meters (820 ft) forward of the weapon. The optimum effective range is 50 meters (165 ft), at which the optimal balance is achieved between lethality and area coverage with a hit probability of 30% on a man-sized target. The weapon and all its accessories are carried in the M7 bandolier. An instruction sheet for the weapon is attached to the inside cover of the bandolier.
The Claymore mine is typically deployed in one of three modes: Controlled, Uncontrolled, or Time-delayed.

Controlled Mode (also known as Command Detonation)
The mine is detonated by the operator as the forward edge of the enemy approaches a point within the killing zone (20 to 30 meters (65 to 100 ft)) where maximum casualties can be inflicted. Controlled detonation may be accomplished by use of either an electrical or nonelectrical firing system. When mines are employed in the controlled role, they are treated the same as individual weapons and are reported for inclusion 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 M57 Firing Device (colloquially referred to as the "clacker") is included with the M18A1 Claymore Mine so that it can be used in the controlled mode. When Claymore Mines are daisy chained together, one M57 firing device can initiate several claymore mines.

Uncontrolled Mode (also known as Victim Initiated Detonation)
Uncontrolled firing is accomplished when the mine is installed in such a manner as to cause an unsuspecting enemy to detonate the mine. Mines employed in this manner must be reported and recorded as land mines. There are many mechanisms that can be used to initiate the M18A1 in uncontrolled mode, including the M142 Multipurpose Firing Device, M5 Pressure Release Device (mousetrap), tripwires, strikers, infrared sensors, acoustic & vibration sensors.

Time-delayed Mode
Time-delayed firing involves the fitting of a short timed fuse and a fuse igniter to allow the mine to be used as a pursuit deterrent. This, anecdotally, may be combined with a CS grenade or bag containing the irritant contained in a CS grenade. The mine is emplaced, quickly oriented on the direction pursuers are most likely to take, and the fuse is ignited before the position is abandoned