Flechettes were first used as an air-dropped weapon in World War I by combatants on both sides. These were about four inches long (10 cm) and weighed a couple of ounces (60 g). Dropped from aeroplanes or Zeppelins over enemy trenches or airfields, these gravity missiles were capable of penetrating a helmet and the wearer's skull. Similar weapons were 'Lazy Dogs' (or 'Devil Dogs'), used by the U.S. in the Korean and Vietnam Wars. These 1 3/4" length (4.5 cm) bomblets were air-dropped at height in canisters by aircraft or scattered from buckets by helicopter crews, reaching high sub-sonic speeds as they fell. Targeted at enemy personnel and unarmored vehicles, the flechette hit the targets with the force of a bullet.
Smaller flechettes were used in special artillery shells called "beehive" rounds (so named for the very distinctive whistling buzz made by thousands of flechettes flying downrange at supersonic speeds) and intended for use against troops in the open - a ballistic shell packed with flechettes was fired and set off by pressure-sensitive detonators, scattering flechettes and shrapnel in all directions. They were used in the Vietnam War by artillery gunners to defend their positions against infantry attacks.
The CBU-107 Passive Attack Weapon is an air-dropped guided bomb containing 3,700 non-explosive steel and tungsten penetrator rods of various sizes. It was designed to attack targets where an explosive effect may be undesirable, such as fuel storage tanks in civilian areas.
10 civilians have been killed in the Gaza Strip by flechette shells since the start of the Palestinian intifada, in September 2000.citation needed The army argues that they have used the weapons very selectively in its fight against terrorism.citation needed
Israeli media reports have said the army uses the shells mainly against mortar crews firing rounds at Israeli civilian settlements.
IDF Spokespersons justify the use of flechette shells by claiming that the use of this weapon is permitted under international law and that "the use of various types of weapons is done according to the judgment of commanders in the field, and based on the threat posed to the security forces." Haim Israeli, Assistant to the Defense Minister, wrote to B'Tselem that "the use of flechette shells in combat is not forbidden. In regards to when this weapon is used, the IDF is aware of the need to balance between military need on one hand, and humanitarian concerns and minimization of damage to the civilian population on the other. The policy regarding the use of various types of weapons is determined based on these considerations.
A member of the international press company Reuters was killed and his vehicle perforated by flechette rounds fired by IDF troops on 16th of April 2008. An explosive round containing the flechettes was fired at the cameraman despite clear markings with the text "press".
Flechette rounds were developed for small arms for a number of reasons. Being very small and light compared to traditional jacketed lead or steel bullets, flechette ammunition weighs less per round, and thus an infantryman can carry more. Another reason was the emergence of lightweight, flexible body armor for the average infantryman. A very high velocity, small diameter projectile is able to easily penetrate body armor. Also its mass-to-piercing-area ratio was much better than that of regular bullets.
However, the flechette has a number of weaknesses that limit its effectiveness as small arms ammunition. They tended to penetrate heavy armor less deeply than heavier, higher momentum rifle bullets. Their extreme light weight caused them to be deflected extremely easily; a single leaf, or even a raindrop, could destabilize a flechette and cause it to tumble wildly. Because of the hard nature of the flechette, it does not deform on impact, and while it penetrates extremely well, it produces very little tissue damage. The last issue with small arms flechettes is accuracy. To fire the finned flechette out of a smoothbore requires the use of a sabot. Since flechettes do not achieve sufficient stability when spun by rifling alone, the main source of stabilization is the fins. When the sabot separates, it can disturb the effectively unstabilized flechette, and cause deviations in its flight. Experiments to reduce problems associated with sabot separation have been performed, such as placing the sabot on the forward portion of the flechette, rather than the rear, and by fitting a sabot stripper in the muzzle to remove it with less disturbance to flight.
An interesting variation of the flechette that addresses its difficulties is the SCIMTR, developed as part of the CAWS project. Also, in 1989 and 1990 the U.S. Army experimented with the Steyr ACR. However, the rifle did not achieve the necessary performance to be considered a viable avenue to pursue.