Ordnance Notes -- by Bob Stoner GMCM (SW) Ret.

M18-Series Claymore Mine

The Scottish Highlanders are famed for their prowess in combat. One of the weapons that was wielded by the Highlanders was a long, two-handed sword called a Claymore. The Claymore carrier, who had to be a very strong man, waded into infantry swinging the blade like a buzz saw and mowing them down like wheat. The equivalent to the 15th Century Claymore is the M18 and M18A1 Claymore directional mine.

The Claymore itself is an olive drab plastic box, slightly convex in the front that measures 3.5 inches high by 1.375 inches wide by 8.5 inches long. It weighs about 3.5 pounds and is filled with 700 steel ball bearings imbedded in a matrix of C4 plastic explosive. The mine has two pairs of folding steel-pronged feet and is fired by a conventional blasting cap. It is used to defend against infantry attacks and to channel enemy movements on the battlefield. The most common employment is in the command-detonated role. SEALs typically use Claymores for ambushes or to cover their withdrawal from contact with a larger enemy force. Claymores can also be employed as booby traps.

A general arrangement drawing of the M18-series directional anti-personnel mine as taken from the technical manual. (Drawing: US Army)

When the mine is detonated, the primary blast pattern describes an arc of 180 degrees wide by 275 yards deep to a height of 8 feet. The kill zone is a pie-shaped wedge of 60 degrees 55 yards deep, a moderately effective depth of 110 yards, and a danger zone out to 275 yards. Secondary blast effects may be felt within the remaining two 60 degree by 275 yard deep areas on either side of the kill zone. The back side of the mine is also dangerous. There is a 180 degree kill zone 18 yards behind the mine and the danger zone extends back another 110 yards.

The mine has a sight to orient it in the direction of the enemy's approach. There are two blasting cap wells, one on each side of the sight. Electric blasting caps are connected to the blasting cable and inserted into the cap wells. The cable is unrolled until the operator is behind cover and at a safe distance from the mine. The M40 circuit tester is inserted in the M57 firing device and the circuit tested. The M40 is then removed and the cable's plug end is inserted into the M57 firing device. When the operator sees that the enemy is within range, he flips the safety bail out of the way and closes the firing lever. The magneto inside the firing device produces enough current to fire the blasting caps and detonate the mine. Non-electric M7 blasting caps, time fuze, and mechanical M1 or M3 firing devices may also be used.

A drawing of the arming and testing setup for the M18-series mine as taken from the technical manual. (Drawing: US Army)

© 2005 Bob Stoner R2