a few new design features. It had a quick-detachable barrel system and an arrangement whereby the spring was mounted inside the bolt in order to make the gun shorter. The Carl Gustav 50-round quad-column "casket" box magazine was lighter and more reliable than the original Lahti 40-round "ranger" drum magazine. Similar applications were used on the Argentinian Hafdasa C-4 and Italian SITES Spectre M4 submachine guns. The Russian company PUFgun makes a 5.45x39mm 60-round AK-74-compatible all-polymer coffin magazine that was based on an abandoned Izhmash prototype. The 70-round 9x19mm Parabellum drum magazine by Koskinen was illegally copied in the Soviet Union for the 71-round 7.62×25mm Tokarev version for the 1934 PPD-40 and was likewise used on the PPSh-41 and PPS-43. Variants A specialized bunker version was also produced in very small numbers (a total of 500 built) in 1941, the barrel shroud end of which was thinner and flattened to allow firing through the narrow ports of defensive bunkers. This version had no shoulder stock and was equipped with a pistol grip. An even rarer version "900 kp 31 psv" was produced for use as a secondary gun in the firing ports of Vickers Alt B Type E 6-Ton tanks, but only a few dozen were built before production was canceled due to the outbreak of the Winter War. Production never resumed, as captured Degtyaryov machine guns proved far superior in this role. Like the bunker version, the tank version had a pistol grip and no buttstock, and it could be quickly removed from the tank and fitted with a standard barrel shroud for infantry use if needed. The tank version remained in the Finnish Army's inventory through the 1980s, despite the tank it was designed for being retired in 1959. Users : KP/26 and KP/31 : 5,000 were bought from 1940–1942. : 1,250 were bought from 1940-1942 of which 500 were delivered. : 32 were bought from Finland, some Swedish m/37-39 were also purchased and 1,400 copies, designated m/41, were manufactured in the kingdom during WWII until Germany disarmed all the Danish army in August 1943. : Used Swedish-made kpist m/37-39s. : 5 KP/-26 were purchased for evaluation. 485 KP-31 were purchased in 1937. : 150 KP/-31 seized from various sources were supplied to French troops during the Phoney War. : Used Swedish-made kpist m/37-39s. : Mix of military surplus and commercial contract guns acquired from unknown sources by