OKMO (Opytniy Konstruktorsko-Mekhanicheskiy Otdel, ‘Experimental Design Mechanical Department’) was the tank design team in the Soviet Union during the early 1930s. Located in Leningrad, it produced the design of the T-26 infantry tank, of which about 12,000 would be produced. Most other designs from the bureau never saw the light of day, but it was here that Mikhail Koshkin, designer of the famous T-34 medium tank gained his early experience. The bureau was gutted in the Great Purge and broken up by the beginning of the Second World War.
In 1930 the Bolshevik Factory No. 232 became home to the AVO-5 tank design bureau, soon renamed OKMO. In 1932, the tank department of the Bolshevik factory, became the new Factory No. 174 (K.E. Voroshilov). This new, independent enterprise was dedicated to the mass production of T-26 tank.
Janusz Magnuski says that in 1932 one of the former departments of the Bolshevik factory became a base for the new independent entity, named in 1935 as Factory No. 185 (S.M. Kirov), under the direction of N. Barykov and Semyon Alexandrovich Ginzburg. The OKMO, for a few months a part of Factory No. 174, moved at the same time to Factory No. 185. The new enterprise was also dedicated to the production of tanks, while the main part of Bolshevik Factory remained focused on production of heavy artillery. Because of the same honorific and the same city of location, the Factory No. 185 is often mistaken in Western sources with Kirov Plant (or Factory No. 100), notably in Sewell's "Why Three Tanks?" and works of Steven Zaloga. They were independent factories; the Factory No. 185 was a home of OKMO bureau (Ginzburg), while the larger Factory No. 100 was a home of SKB-2 (Kotin, known for KV line of heavy tanks). In 1941, because of German threat, parts of both factories were moved to Chelyabinsk, where the large complex was given the name Chelyabinsk Kirov Plant No. 100 (unofficially Tankograd), and continued the production of Kotin's design line.