The physics of a 'great sword' turned into a wall of steel

Cultures · Published 3 October 2026 Swipe more like this →

In short: Most landmines are designed to explode underfoot, but the Claymore mine is built for area denial. It uses a specific physical phenomenon to project a lethal fan of steel balls, turning a single explosive charge into a directional spray that can strike targets up to 300 feet away.

The Claymore's effectiveness relies on the Misnay–Schardin effect. Discovered during World War II by József Misnay and Hubert Schardin, this principle dictates that when a sheet of explosive detonates against a heavy backing surface, the blast is primarily directed away from that surface in a single direction. While Schardin originally explored this for anti-tank weapons and 'trench mines,' it became the foundation for modern directional fragmentation.

The transition from theory to weapon involved significant engineering hurdles at Aerojet starting in 1954. Early attempts, like Canada's 'Phoenix' mine or the original M18 Claymore, were too large or lacked sufficient range. The goal was to create a weapon weighing under 3.5 pounds that could deliver 58 foot-pounds of kinetic energy—the threshold for potentially lethal injury—at a distance of 50 meters. Engineers discovered that using hardened steel balls was counterproductive; they shattered into useless shards upon detonation and allowed the blast energy to 'leak' between them.

The breakthrough came when William Kincheloe suggested using soft 1/8-inch steel 'gingle' balls. Instead of shattering, these balls deformed into aerodynamic shapes similar to .22 rimfire projectiles. By setting these balls into a Devcon-S steel-filled epoxy resin matrix behind a layer of C-4 explosive, engineers ensured the blast energy was converted into forward velocity. This configuration allows the mine to project fragments at 3,900 ft/s in a 60° arc, achieving an optimal balance between lethality and area coverage.

Even the aesthetics were dictated by physics and chemistry. The iconic 'FRONT TOWARD ENEMY' marking was added for safety, while the sight was simplified to a knife blade because fumes from the explosives and adhesive corroded more complex mirror systems. Today, it remains a staple of infantry tactics, capable of being daisy-chained with a single 'clacker' firing device.

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