BSA Welgun The Welgun was a prototype submachine gun developed by the British irregular warfare organisation , the Special Operations Executive . Although it performed well in tests , it was never adopted , and was produced in small numbers only . Development . When issuing arms to resistance fighters throughout Europe , SOE favoured short - range , rapid fire , cost effective weapons which required little training to use , or maintenance in the field . Initially , they favoured the British Army issue crude and cheap Sten sub machine gun , but this weapon perhaps went too far in the directions of cheapness and simplicity . Early marks were notoriously unreliable and prone to accidental discharges , and some were so badly manufactured that they were issued to resistance fighters with " burrs " in the barrel or working parts which might even cause the weapon to explode when fired . One of SOE ' s research departments , the " Inter Services Research Bureau " at Station IX in The Frythe , a former hotel outside Welwyn Garden City , sought a weapon more suited to the organisation ' s needs in early 1942 . They had already produced the prototype Norm Gun ( named after its inventor , Eric Norman ) but this was too expensive for large - scale manufacture . A cheaper alternative was produced by F . T . Bridgman . Various other official bodies , and the Birmingham Small Arms factory also had input . In early 1943 , Sir Charles Hambro , the Director of the SOE , sought permission to have the weapon put into large - scale production . Six pre - production models were tested against comparative weapons , such as the Sten Mk . IV . The Welgun was less reliable in poor operating conditions such as mud or dust , because the first models had been made with too close tolerances . It was however , more accurate and easier to use . Peter Kemp of SOE describes using a Welgun in Albania in his memoir " No Colours or Crest " , though it would jam during an ambush . Later pre - production models had more generous tolerances and were as reliable as the Sten under conditions of deliberate abuse . Various Allied commando and Army organisations were enthusiastic about the weapon . In the event , the Sten Mk . IV was chosen for mass production over the Welgun , though it did not enter widespread service either . No official reason for the Welgun ' s rejection has survived . Design and Characteristics . The weapon was a fairly conventional blowback design . It used the same 9mm Parabellum cartridge as the Sten . Since this round was also used by the Axis , resistance fighters could obtain ammunition from enemy sources . The Welgun used the same 32 - round single - feed magazine as the Sten , a potential source of trouble as this design was unreliable in service . The magazine fed vertically , rather than sideways as in the Sten . The Welgun had a folding stock . When this was folded to lie over the barrel and body of the gun , the overall length of the weapon was barely 10 inches , allowing easy carriage and concealment . The Welgun also had a wooden pistol grip , and vestigial wooden foregrip , which contributed to its accuracy and balance . Name . The " Wel - " prefix to the weapon ' s name derives from Welwyn Garden City , near which Station IX was located . The prefix identified several weapons and other items of equipment designed or produced by this establishment , such as the Welrod assassination weapon .