The lead-up to World War 2 (1939-1945) provided many weapons with the avenue needed to see serial production and combat service - some out of sheer desperation due to shortages. During the late 1930s, the nation of Sweden moved ahead in adopting the "Kg m/40", an automatic machine gun design intended for portable squad level service, as a means to fill its light machine gun requirement. It was a largely conventional weapon utilizing gas operation and full-automatic fire while being chambered for the local 6.5x55mm Swedish service rifle cartridge. This cartridge was, itself, adopted as early as 1894.
The m/40 went on to have a short service life in the scope of the grand war, also seeing local manufacture in Nazi Germany during the conflict as the "Maschinengewehr 35" (MG35) or simply referred to as "Knorr-Bremse" after the Berlin-based company that produced it. Small German stocks were shipped to Finland during its Winter War against the Soviet Union and Norway rounded out the list of known operators of the weapon. In German service, the guns were replaced by various types of Czech light machine guns.
The m/40 was of largely metal construction, this seen at the receiver, the barrel, and gas cylinder. The gas cylinder sat over the barrel with a noticeable gap witnessed between the cylinder and barrel. A carrying handle allowed for ease-of-transport while it also doubled as a barrel-changing grip in the sustained fire role. Sling loops also aided the operator during marches, the loops found at the gas cylinder and under the shoulder stock. The stock and grip handles used wood, the grip being nearly vertical in its design and the stock showing some smoothly contoured lines. Iron sights were fitted over the receiver and at the extreme forward end of the gas cylinder for ranged fire. Feeding was by way of a 20-round detachable box magazine inserted into the left side of the receiver, spent shell casings ejecting from a port along the right. The magazines were based on the American BAR straight boxes though slightly revised to a Swedish pattern - the Swedes also produced a version of the American BAR light machine gun locally as the "Kg m/37". Rate-of-fire was 490 rounds per minute with a muzzle velocity of 2,600 feet per second.
The Swedish patent for the weapon was recorded around 1933-1934 and early forms were rebuffed by the government. The design then fell to Knorr-Bremse of Berlin, Germany, who - up to that time - had specialized in automotive brake equipment and were certainly not recognized gunsmiths. Nevertheless, they were able to interest the Waffen-SS into purchasing a small stock of the Swedish design. Their stay in the German inventory was short-lived once more effective products emerged. They were then used up by the Finns in short order. Swedish Army service involving m/40s was also rather brief.
Knorr-Bremse's inexperience in military gun-making eventually showed through however. The guns were of a largely sound Swedish design though their operational history became somewhat marked by the failure of some of their individual components - chief among these being misfires through improperly set safeties and shoulder stocks coming loose in action due to the vibrations when firing. Overall, this made the m/40 guns largely forgotten in the grand scope of World War 2 firearms.