Bullpup 1945-1970: history of experiments

By Maxim Popenker

British experimental 7mm EM-1 “Cobra” bullpup assault rifle, ca.1947

This article is about history of bullpup evolution from the end of WW2 and until early 1970s, stopping just before adoption of two first really mass produced bullpup rifles – Austrian Steyr AUG and French FAMAS. In previous article we briefly examined early history of bullpup small arms, from Thorneycroft and Godsal rifles of 1902 and up to British developments late in the World War Two.

British soldier with experimental 7mm EM-2 bullpup assault rifle

As we discussed before, towards the end of WW2 British engineers were deeply engaged in the development of bullpup rifles, manually operated, semi- and full-automatic. It was clear that British army was in need for a more modern rifle to replace its obsolete SMLE bolt action rifles. British experts started with the development of the new cartridge, a cleverly designed intermediate round that would be effective up to 600 yards in an infantry rifle and up to 1000 yards in an universal machine gun, while being noticeably lighter and generating less recoil than any existing service rifle round of the allied forces (.303 British or .30-06 US or 7.62x54R Russian). With new 7x43mm round at hands, British army initiated development of a new rifle. At least three domestic teams participated in the race – two from government facilities (lead by Thorpe and Janson) and one from BSA Ltd, a private gun-making company. Only the latter weapon was of traditional layout, the other two, known as EM-1 Cobra and EM-2 Mamba, were of bullpup layout. EM-1 rifle, designed by the team led by Thorpe (of the STEN fame) was heavily based on German developments, utilizing many stamped steel components and roller-locked gas operated action, inspired by Stg.45 from Mauser. The EM-2, designed by Janson team, was produced by more traditional technologies and featured flap locking and gas operated action. The EM-2 proved to be most successful of the three weapons, and in 1951 it went as far as being officially adopted for British service as “Rifle, Automatic, caliber .280, Number 9 Mark 1”. However, with the changes in the British government this decision was shortly reversed in sake of maintaining caliber compatibility with US armed forces. Later on, attempts were made to convert EM-2 rifle to the new American “7.62mm T65 light rifle ammunition”, which later was adopted as 7.62×51 NATO. For some reasons, this conversion proved to be unsuccessful, and in around 1955 British army adopted Belgian FN FAL rifle of traditional layout as 7.62mm L1A1 SLR. Of cause, it is worth to note that early prototypes of the FN FAL rifle were produced for British 7x43mm intermediate cartridge and in two alternate layouts – standard and bullpup. 7mm bullpup FAL rifles were widely tested during early 1950s, but found no takers; as a result, production versions of this highly successful rifle were all confined to traditional layout.

7mm experimental FN FAL bullpup rifle, ca.1950

While British and Belgian bullpups of the early post-WW2 period are well known, similar Soviet developments of the same era are quite obscure. Soviet designers experimented with bullpup-configured antitank rifles before WW2, but none of these was ever adopted. However, during early stages of development of a new family of intermediate cartridge (7.62×39 M43) small arms Soviet army tested several assault rifles of bullpup layout.
One of the earliest Soviet bullpup assault rifles was designed by Korovin and submitted to military trials in 1945. It was somewhat roughly looking weapon with annular gas piston and rotary bolt looking. It is not known why it was rejected, but about a year or two later another bullpup rifle was submitted to next stage of trials. It was designed by a talented but somewhat unlucky designed Korobov. His rifle, known as TKB-408, also featured gas operated, locked breech action with tilting bolt. It was more or less on par with contemporary British developments. One prominent feature of the TKB-408 was location of the magazine catch, which was placed at the bottom of the pistol grip, requiring special magazines. Like many other contestants, TKB-408 finally lost in trials to the now famous Kalashnikov AK-47 assault rifle of traditional layout, which was officially adopted for Soviet army service in 1949.

7.62mm Soviet experimental assault rifle by Korovin, 1945

During late forties, American designers also were trying to develop a new generation rifle, a lightweight select-fire weapon firing new, lighter but still quite powerful .30-caliber (7.62mm) ammunition. Among many experimental weapons, bearing various “T” indexes between T20 and T48, one T31 prototype deserves our attention. Developed around 1949 by famous gun designer John Garand, this slender rifle featured indigenous gas operated action with annual gas piston. It was briefly tested but never went past experimental stage of development.

7.62mm US T31 experimental assault rifle, 1949

During 1950s, a lot of bullpup development was conducted in France. At the time, several French manufacturers competed in development of a new automatic rifle for French armed forces, to replace somewhat obsolescent MAS-49 rifle. It is interesting that several designs were developed simultaneously in traditional and bullpup layouts. Experimental rifles from AME, MAS and MAT were produced as bullpups, but, apparently, neither performed satisfactory, and in 1956 French army settled on a rather conservative MAS 49/56 semi-automatic rifle of traditional layout.

French experimental bullpup assault rifle, designed at MAS in 1954

By late fifties most of the NATO and Warsaw pact armies have adopted new generation of infantry rifles. For NATO, these included 7.62x51mm rifles such as M14, FN FAL and HK G3. For Warsaw pact, Soviet AK and SKS, both firing less powerful 7.62x39mm ammo, became the mainstream, with Czechoslovak army running their own small side show with indigenous SA Vz.58 rifle of same caliber. All of these weapons were of traditional layout, but work on bullpup continued. The main drive for further development of bullpups were requirements set forth by mechanized troops, which would ride to the battlefield in confined spaces of armored personnel carriers (APC) and recently born helicopters. Folding stocks on traditional rifles offered only a partial solution, while bullpup rifles offered “full-size” firepower in noticeably shorter weapon.
Despite relatively compact size of the Soviet Kalashnikov AK and AKM rifles, and existence of even more compact folding stock versions known as AKS and AKMS, several Soviet designers attempted to develop bullpup rifles firing same 7.62x39mm ammunition. One of most notable Soviet designs of 1960s was the experimental TKB-022 assault rifle, designed by already mentioned Gennadii Korobov in around 1962. This spectacular weapon featured plastic outer housing built around compact steel receiver (more than a decade before Steyr AUG), extreme rearward location of box magazine, and, at last but not least, forward ejection of spent cases, ensuring safe firing from left shoulder or from inside of an APC. To achieve maximum barrel length possible within limitations of overall weapon size, Korobov used unusual action with vertically sliding breechblock (similar to that of single shot “falling block” rifles of bygone era). Ejection, extraction and feeding of fresh cartridges were ensured by a special U-shaped part, connected to the gas piston. This allowed placing magazine as far rearward as possible. Spent cases, once extracted from the barrel, were cammed out of barrel line and pushed forward and through the ejection tube that run towards the muzzle. The TKB-022 rifle went through several modifications and versions which spanned through most of 1960s. Ultimate version of the TKB-022 was chambered for then-experimental 5.6×39 ammunition, which later evolved into 5.45×39 M1974 cartridge, but TKB-022 rifle never went past prototype stage. The same design bureau, located in the city of Tula, also brought up 7.62×39 TKB-011 bullpup rifle, designed by Afanasiev. It was developed during same timeframe as TKB-022, using similar concepts and materials, including red-brown colored plastics for outer shell. TKB-011 also featured “safe” ejection pattern, and its ejection port was located on the right side of the gun, pointing forward and to the right. Like the Korobov design, TKB-011 survived only as an experimental prototype in Tula arms museum.

7.62mm Soviet TKB-022 experimental assault rifle by Korobov, 1962

7.62mm Soviet TKB-011M experimental assault rifle by Afanasiev, 1964

It appears that interest to unorthodox bullpup rifles was quite widespread across Soviet small arms design bureaus. Another well-known gun design organization of the time, located in the city of Kovrov, during early 1960s brought several quite unusual designs, invented by designer Konstantinov. One of his conceptual works, known as SA-01, was submitted to factory tests in 1963. The main goal was to make rifle as controllable in off-hand full auto shooting as possible. As a result, SA-01 was designed as an “inverted bullpup”, with pistol grip being above the receiver. Apparently, this layout was a bit too radical, as in 1965 Konstantinov submitted his next design, known as SA-001, which featured conventional bullpup layout with pistol grip and foregrip located below the barrel. Like their counterparts from Tula, bullpup rifles from Kovrov remained in experimental stage only.

7.62mm Soviet SA-01 experimental assault rifle by Konstantinov, 1963

7.62mm Soviet SA-001 experimental assault rifle by Konstantinov, 1965

Late sixties saw some bullpup developments from USA. During this period US Army sponsored a highly ambitious “Special Purpose Individual Weapon” (SPIW ) program, which, despite its “special purpose” moniker was intended to provide soldiers with “one gun does it all” weapon that combined flechette-firing rifle and multi-shot 40mm grenade launcher. One of main contenders during entire SPIW program was bullpup rifle developed by Springfield arsenal. Early versions of the Springfield SPIW rifle were especially interesting due to their modular design – same receiver with barrel, action and magazine housing could be easily converted from conventional layout to bullpup and back. However, it soon was discovered that in traditional layout new rifle would be too long and with balance too forward (especially with 40mm grenade launcher attached), and later prototypes were produced only as bullpups. The Springfield SPIW rifle in is final form was a long and angular weapon, with unusual tandem magazine holding 60 rounds of flechette-loaded cartridges. Due to unrealistic requirements, set in the SPIW program, and a number of serious issues with flechette ammunition, no weapons from this program ever reached production status.

early drawing of the modular SPIW rifle by Springfield armory, USA, 1964

The last weapon to complete our round-up of the quarter century of bullpup experiments (1945-1970) is another US prototype, known as “Individual Multipurpose Weapon” (IMP-221) or GUU-4/P, developed during late sixties by Dale Davis of USAF Armament Laboratory. Intended as a Personal Defense Weapon for air crews, this little gas-operated bullpup featured no shoulder stock, and was intended for single-hand firing. To achieve ambidextrous handling, its pistol grip could be swung sideways to one or other side, placing magazine at an angle to the vertical plane, to clear the shooter’s arm. Only few prototypes of IMP-221 were built by Colt under contract with USAF, and then the latter lost interest in the development, leaving US military pilots with pistols or revolvers as primary defensive sidearms for foreseeable future. It is worth noting that modified IMP-221 design was brought to commercial market during 1970s as Bushmaster Arm Pistol, chambered for more powerful .223 Rem ammunition.

5.6mm experimental IMP-221 personal defense weapon, designed in USA for US Air Force, 1969

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