After working for the railway Aimo Lahti joined the Finnish Army as a Master Armorer in 1921. He was influenced in this decision by Captain Rosenholm. In 1922, he started to design the Suomi M-31 SMG after examining the Bergmann MP18, which had many design problems and was expensive. The new design was revolutionary because the reliability, accuracy, and rate of fire were excellent. The first 200 Suomi SMGs were produced in 1922. After the prototypes were made, he was ordered to work under the control of the Ministry of Defence and to design a light machine gun, which eventually would be the Lahti-Saloranta M/26. He then improved the Mosin–Nagant rifle by designing the M/27 "Pystykorva" "Spitz", named for its foresight guards' resemblance to the dog breed's ears. This rifle was later issued to the Finnish Army as their service rifle.