Army engineers patent limited range bullet that self-destructs

Researchers working for the U.S. Army have been award a patent for a revolutionary limited range bullet that self-destructs.

Three employees of the U.S. Army Armament Research, Development and Engineering Center (ARDEC) were awarded the patent for the proof-of-concept projectile, which aims to reduce collateral damage.

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Designed for use in close combat areas such as urban fighting, the projectile could reduce the risk of stray bullets hitting civilians or friendly forces. Researchers say that the bullet could also be useful on firing and training ranges and could potentially be used by civilian police.

"In today's urban environments others could become significantly hurt or killed, especially by a round the size of a .50 caliber, if it goes too far," said Stephen McFarlane, one of the ARDEC employees awarded the patent, in an Army press release.

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The bullet contains both pyrotechnic and reactive material, according to the patent filing, with the pyrotechnic material ignited at launch. “The pyrotechnic material ignites the reactive material,” the patent explains. “If the projectile reaches a maximum desired range prior to impact with a target, the ignited reactive material transforms the projectile into an aerodynamically unstable object.”

The idea here is that once the bullet has reached its range, it simply drops to the ground. McFarlane noted that the distance at which the round “disassembles” can be adjusted based on the type of reactive material used.

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In one concept outlined by the researchers, the projectile’s copper jacket melts, producing a highly irregular shape. In another, the cylindrical part of the bullet separates from its base and its “penetrator,” or tip.

The proof of concept is being applied to .50 caliber ammunition, but could theoretically be used in various calibers of small arms munitions, according to the Army.

In modelling and simulation tests, the bullets demonstrated “pre-destabilization trajectory” similar to the .50 caliber M33 round, with a maximum range of less than 6,561 feet.

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However, in its press release the Army noted that funding for the project has ceased. Nonetheless, the ARDEC engineers hope that the concept will resurface with the ongoing need to develop greater technology for troops. "This was the first patent we applied for that has been approved,” said McFarlane. “That in itself is an accomplishment."

McFarlane, Brian Kim and Mark Minisi filed collectively for the patent on May 7, 2013, and were notified of its approval last year, according to the Army.