Staff Writer (Updated: 5/9/2016):
Initial reactions were positive though the m/21 held a propensity to overheat its barrel assembly through prolonged fire. Thusly, Carl Gustafs Stads Gevarfaktori (now Bofors) took to developing a quick barrel changing function to the m/21 which allowed the operator to replace the barrel by managing a simple latch at the front of the receiver. The attached carrying handle facilitated handling of the hot barrel during the process. The wooden handguard of the original BAR was subsequently dropped. All other BAR functions remained intact. As such, Carl Gustafs ended producing the m/21 under its new designation of KG m/37 in 1937, promptly adopted by the Swedish Army in turn. Older m/21 marks were brought up to the new standard when possible.
By this point, the m/37 now truly fulfilled the light machine gun role, save for its limited 20-round magazine which was never addressed. A prototype belt-fed variant was experimented but never brought to service. Regardless, the m/37 remained in a frontline role until the adoption of the excellent Belgian Fabrique Nationale FN MAG General Purpose Machine Gun of 7.62x51mm NATO standard caliber during the post-World War 2 "Cold War" years. Even then, the m/37 existed in a reserve role within the Swedish Army inventory for a number of years. The FN MAG became widely available in 1958.