For the 19th-century German military weapon, see Needle-gun.

A needlegun, also known as a needler, flechette gun or fletcher, is a firearm that fires small fin-stabilized, metal darts. The first projectiles in early gun systems dating from the 14th century were typically hand wrought iron flechettes wrapped in a leather sabot. However, due to the expense and trouble of making these darts in a pre-industrialized society, they were soon replaced with the less accurate stone cannon ball. Flechettes again came into mass use in World War I. In addition to being dropped from airplanes in this war, they were also used as ammunition for the first electromagnetic rail gun by the French against the Germans. More recently, several flechette weapon systems have been developed, but none appear to be in mass production. However, flechette ammunition encased in a sabot is available for the M-16, shotguns and other weapons.

This weapon is featured in numerous works of fiction, notably:

• Michael Moorcock's Jerry Cornelius stories (after which it is also the title of a Hawkwind song)
• William Gibson's Neuromancer et seq.
• Harry Harrison's Stainless Steel Rat stories
• The weapon named Reason in Neal Stephenson's Snow Crash
• Terry Pratchett's Strata
• Marvel Comics' Nick Fury, Agent of SHIELD
• Larry Niven's A Gift From Earth
• William C. Dietz's The Flood
• Zachary M. Emami's The Needle Revolution

Theoretically, the advantages of a needlegun over other projectile weapons are its compact size, high rate of fire, and ultra-high muzzle velocity. A needlegun takes advantage of the principles of kinetic energy and conservation of momentum, allowing a low-recoil delivery system to inflict significant damage to a target. Recoil is governed by momentum, which is the product of velocity and mass. By conservation of momentum, the change in momentum of the gun must equal the change in momentum of the projectile. The needle projectile has a very small mass, so its large change in velocity does not result in much recoil (change in velocity of the gun itself) since the gun has a mass much larger than the mass of the needle. Damage inflicted is related to the kinetic energy imparted by the projectile, which is 1/2 the projectile's mass multiplied by its velocity squared. Since the needle has a very high velocity and a negligible mass, recoil is minimized at little cost to the kinetic energy of the projectile and its damage potential. The high rate of fire allows the user to fire many needles quickly with a minimal loss of accuracy due to recoil effects, giving the needlegun supposedly large damage potential and precision in combat.

Most hypothetical needlegun designs are solid state, meaning that the delivery system has no moving parts other than the projectile itself. For instance, see coilgun and railgun.

Computer games

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A Nailgun and Super-Nailgun were prominently featured as weapons in Quake. They were the equivalent of machine-gun style weapons that were able to fire rapidly by holding down the trigger. Revolution contains a nailgun, but it fires only a single barrage before pausing to recharge.

Fallout 2 included a Needler weapon, which shot poisoned darts. A Tiberium-based Flechette Gun was also usable in Renegade.

The Jedi Knight series features a weapon called the Golan Arms FC1 Flechette which fires metallic darts.

Bungie's Marathon Infinity featured the KKV-7 submachine gun, which fired 4mm flechettes from a 10mm cartridge and was usable underwater.

More recently, the Halo also featured a weapon known as the "Needler". This iteration fires glasslike, explosive projectiles which automatically seek out a target along their initial trajectory. The projectiles may turn sharply when near a target, or when the projectiles strike a surface at an oblique angle.

Also, in Devil May Cry, the main character Dante has a weapon called a needle gun. It is the only weapon he can use underwater.

The junker uses a 40mm high-explosive flechette gun as his main weapon in the Kinetic Novel Planetarian. Fictional firearms