Bullpup

A bullpup is a firearm with its action behind its trigger group. This configuration permits a shorter overall weapon for a given barrel length. This maintains the advantages of a longer barrel in muzzle velocity and accuracy, while improving maneuverability and reducing weight.

The origin of the term "bullpup" for this configuration is unclear. In 1957, the word was reported to denote a target pistol, particularly one with a fancy stock.

The bullpup design places the gun's action behind the trigger, usually in front of a short buttstock. The entire magazine is often also located behind the trigger group, though it is only necessary for the weapon's feed location to be located there for it to be classified as a bullpup; in some designs such as the Heckler & Koch G11 and Neostead the magazine or magazines extend forward rather than downward.

The configuration decreases the firearm's overall length while retaining the same barrel length which allows for better maneuverability in confined spaces.

An often cited shortcoming of the bullpup configuration is spent casings being ejected into the face of a left-handed shooter, preventing effective use. This is solved on some designs with ejection downward (FN P90) or forward (FN F2000,Kel-Tec RFB).

Being held closer to the body, a bullpup causes less arm fatigue and allows faster reaction time from a lowered position. However, its rear-weighted design lacks balance, inducing muzzle rise and inaccurate automatic fire. In addition, shorter weapon length results in a shorter sight radius, further impairing accuracy at distance, as well as reducing bayonet effectiveness in close combat. Also, due to the forward assembly and the necessary trigger linkage, bullpup trigger pull characteristics are often criticized.

The concept was first used in bolt action rifles such as the Thorneycroft carbine of 1901, although the increased distance from hand grip to bolt handle meant the decreased length had to be weighed against the increased time required to fire. It is known to have been applied to semi-automatic firearms in 1918 (6.5 mm French Faucon-Meunier semi-automatic rifle developed by Lt. Col. Armand-Frédéric Faucon), then in 1936 a bullpup machine pistol was patented by the Frenchman Henri Delacre.

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