The story of Prvi Partizan starts at the beginning of the XX century. In 1927, the founder of the factory, Jakob Posinger, in cooperation with the army and the government of the Kingdom of Yugoslavia, moved his workshop from Kranj (Slovenia) to Uzice. After the purchase of machines, the workshop was equipped for the production of hunting rifles and pistol ammunition. It started work on 1st of May 1928 in facilities located in the "Stevan Nemanja" military barracks in Krcagovo. During the first two years 150 workers worked in the factory.
In 1935 the authorities of the town of Uzice decide to give mr. Posinger, as a present, land for the building of a new factory. The laying of the foundation stone on June 20th 1935 marked the construction of the first private factory of this kind in the Balkans. The official name of the factory was "Factory of Arms and Ammunition in Uzice" - FOMU.
In the beginning FOMU produced several different ammunition calibers including Central 7mm, 9mm, and 12mm; Browning 6.35mm, 7.65mm and 9mm, Serbian Nagant 7.62mm, hunting ammunition cases for smokeless powder, as well as single-barreled and double-barreled hunting rifles in calibers of 12, 16 and 20. In the following years the factory started production of military rifles in the 7.9mm calibers and ammunition for government 9mm Short Pistols. Also, military rifles were repaired in FOMU.

At the beginning of World War II the occupying forces heavily damaged the production facilities and destroyed the administrative building to the foundation. The town was liberated on September 24th 1941 and the arms factory started to work under the control of the Partisan military authorities. The ammunition production facilities and tool shop was moved to the underground tunnel safe of the National Bank and other production facilities were moved to plants in the town surroundings.
During that period Uzice was the only town in Yugoslavia, and possibly in Europe, in which an arms factory was working under occupation. It had a very important role in equipping units of the National Libearation Army and it was known for its production of "thin and long rifles" (partisan rifles) and hand grenades. The factory stopped working on November 22rd after an explosion caused by sabotage claimed the lives of more then 120 persons.
On September 5th 1947, the factory in Uzice was renamed "Prvi Partizan" and it became a state owned company.
At the end of 1970s company Prvi Partizan had started works on construction of new buildings and infrastructure. These caused enlarging capacities and introduction of new articles in production.