Bullpup is a firearm configuration in which the action and magazine are located behind the trigger. This increases the barrel length relative to the overall weapon length, permitting shorter weapons for the same barrel length, saving weight and increasing maneuverability. It alternatively allows for longer barrels on weapons of the same length, improving muzzle velocity. Higher muzzle velocities result in flatter trajectories, a longer effective range, and, in some cases, increased lethality.
The first significant bullpup assault rifle came from the British program to replace the service pistols, sub-machine guns, and rifles. In the two forms of the EM-1 and the EM-2, the new rifle concept was born as a result of the experience with small arms that was gained during the Second World War. It was obvious that the modern warfare would require the infantry to be armed with light, selective fire weapon with effective range of fire much longer than of submachine gun, but shorter than of conventional semi-automatic or bolt action rifles. The choice of bullpup design was a necessity to retain accuracy while reducing overall length. With none of the firing difficulties a bolt-action bullpup achieved, giving a short, long-ranged rifle the bullpup configuration was an obvious option. The EM-2 was adopted by the UK in 1951 as the world's first (limited) service bullpup rifle but was promptly displaced by the adoption of the 7.62 mm (0.308 in) N.A.T.O. cartridge.
A 7.62 mm caliber experimental assault rifle was developed by Korobov in the Soviet Union around 1945, and a further development, the TKB-408 was entered for the 1946-7 assault rifle trials by the Soviet Army, although it was rejected in favour of the more conventional AK-47.
After these failures of the bullpup design to achieve widespread service, the concept continued to be explored (for example: a second Korobov bullpup, the TKB-022). However, it wasn't until over a decade later when bullpups burst onto the scene with the Steyr AUG (1977) and the slightly less widespread FAMAS (1978). The Steyr AUG is often cited as the first successful bullpup—achieving service among various services of over twenty countries, and becoming the primary rifle of countries such as Austria and Australia. It achieved an ingenious weapon sometimes described as 'ahead of its time', and it combined, for the first time, bullpup configuration, polymer housing, dual vertical grips, telescopic sight as standard, and a modular design. Highly reliable, light, and accurate, the Steyr AUG showed clearly the potential of the bullpup layout. The arrival of the FAMAS, and its adoption by France emphasized the slide from traditional to bullpup layouts within gun designs, although the increased complexity, difficulty of cleaning, and decreased reliability (as the Gulf War made clear) of the lever-delayed-blowback, as well as the lack of innovations such as telescopic sight and modularity, helped prevent significant acceptance of the FAMAS beyond its nation of origin.
Since the capabilities and widespread usage of these new bullpups became clear, bullpup rifles rapidly gained popularity among military rifle makers. The British restarted its bullpup ambitions with the SA-80. Despite persistent reliability problems, it was redesigned by Heckler & Koch into the L-85, and it rose to become a reliable, accurate although a rather heavy battle rifle. Having gained service among some of the most militarily powerful Western countries, bullpup rifles became common new battle rifles. The Singaporean SAR-21 was a highly reliable and accurate example, that addressed many flaws with bullpup rifles by using a stiff sliding plate to increase trigger responsiveness, and by using a shell deflector to achieve an (imperfectly) ambidextrous weapon. IMI of Israel made the move to bullpup. Having learned from the extensive combat experience of a highly efficient, well-trained military about the importance of light-weight, high accuracy, and small size, the Israeli military developed a bullpup rifle—the Tavor (TAR-21). Epitomizing the standard of modern firearms, the Tavor is extremely light, accurate, and reliable (requiring stringent reliability standards to avoid being jammed by the prevalent sand of the Middle East), and has garnered demand among other countries, notably, India. Incidentally, the Tavor shares many similarities with the SAR-21. The modern success of bullpups has been emphasized by the adoption of bullpup rifles by two major militaries, the Iranian army and the People's Liberation Army of China, of the Khaybar KH2002 and the QBZ-95 correspondingly.
The future of bullpups appears bright. More bullpup battle rifles are now being developed than rifles laid out traditionally. Even sniper rifles, such as the Polish Bor, have gained the bullpup layout. Some cite the increasingly urban nature of warfare as a reason for their increased popularity, their short length being useful in tight quarters. With increasing innovations (such as the forward ejection system of the FN F2000), often cited problems with bullpup rifles seem soon to disappear. Indeed forwards ejection, or other ambidextrous ejection systems, such as downwards ejection, may be the future for bullpup rifles—and even for battle rifles in general (the forward ejection mechanism of the upcoming Kel-Tec RFB supports this idea, as does the downward ejection of the FAD assault rifle, and the high compatibility of forward ejection with the US DOD's Lightweight Small Arms Technologies).
|Mechanisms typically eject casings to the side. This means that a conventional bullpup design can only be fired from one side of the body, or the casings will hit the operator in the face. This restricts the abilities of left-handed shooters, and forces a shooter firing to the right around a corner to expose more of his body (a particular danger in urban warfare). While some bullpups can have the ejection port switch sides during disassembly, this is not feasible during a combat situation.||The ability to shoot left-handed is often deemed less important than greater accuracy and smaller size. Otherwise, some bullpup designs address this issue by allowing the side of ejection to be switched during disassembly (e.g. the FAMAS, Tavor and Steyr AUG), while others, like the FN F2000, A-91, and the Kel-Tec RFB Rifle, eject forward, providing complete tactical flexibility, even when shooting around corners. Still others, like the FN P90, achieve similar flexibility by ejecting downward. A few bullpup weapons have been designed that do not eject casings at all, such as the Heckler & Koch G11, though none of these have yet been widely produced.|
|Bullpups tend to have a heavy and sluggish trigger pull, due to the long flexible rod or similar system required to span the distance between the trigger and the firing mechanism.||This is fairly minor compared with gains in accuracy and compactness. Furthermore, some bullpups, such as the SAR-21 and the Tavor, use a stiff sliding plate to overcome this.|
|A bullpup weapon's center of balance is to the rear or directly above the trigger hand, rather than between the user's hands as with traditionally orientated rifles. This is often labelled harder to carry and uncomfortable, with possibly greater muzzle climb.||The shorter length allows for faster aiming and reduced weight strain on the soldier's arms, both due to the principle of moments.|
|Bullpups are often cited as having awkward magazine changes due to the more closed arm position required to insert the magazine.||This awkwardness is often cited to be due to trained habits rather than the weapon itself. Many armies, such as the British Army, who train with a bullpup weapon almost exclusively, would probably find reloading a traditional weapon awkward, due to force of habit. The farther back center of weight helps a reloading soldier to place some weight on the shoulder rather than the trigger arm. This, combined with the shorter length (see above), can reduce arm strain while reloading. The more closed position of the magazine and smaller weapon makes changing the magazine in small spaces (such as a vehicle) easier. In modern warfare, this is becoming ever more important.|
|Farther back magazines and closer muzzles cause difficulties over viewing the magazine and the amount of ammo it holds, reduced reach in bayonet fighting, and closer muzzle blast.||If these problems were really deemed serious enough, gun manufacturers would be striving to make guns as long as possible. The magazine viewing difficulty is barely an issue, and is easily overcome with training. A closer muzzle blast and reduced bayonet reach can easily be fixed by using a longer barrel (with the added advantage of greater accuracy), but the rarity of bayonet fighting and the awkwardness of greater length make this as unattractive as having the greater length of traditionally laid-out weapons.|