The official designations of Russian and Soviet artillery consists of three sequential parts – weapon caliber, weapon type, and finally a unique identifier for each variant. This system is descended from the later Russian Empire, but its first (caliber) and third (unique identifier) components were changed several times over the years. Origin - Russian Empire After abolishing the old system of designations based on projectile or gun weight during the early years of the 20th century, Imperial Russian Army designation policy was simplified. The first component of the designation was caliber in inches or lines, then type of a piece with optional producer’s name and attributes such as regimental, divisional, siege, field, fortress, etc. follows and the year of adopting the piece onto Army service finishes the name. E. g. howitzer with Schneider designation O. C. 6″ Bas became 6-дюймовая крепостная гаубица обр. 1909 г. (6-inch fortress howitzer Model of 1909) and Canon de 42‴ Schneider was designated 42-линейная полевая тяжёлая пушка образца 1910 года (42-line heavy field gun M1910). Metric system (1917) After the October Revolution, the first change in this new system took place, when Soviet Union officially adopted the metric system and abolished old non-metric measurement units. From this point until the present caliber is expressed in millimeters; the fractional part of the caliber was rounded to the nearest integer value. In some cases, the attributes were simplified. Examples of these modified designations include 76-мм дивизионная пушка обр. 1902 г. (76 mm divisional gun M1902, formerly 3-inch divisional gun M1902) or 152-мм пушка обр. 1910 года (152 mm gun M1910, formerly 6-inch siege gun M1910). Modernized weapons The industrial growth of the Soviet Union during the late 1920s and the 1930s allowed the modernization of older or obsolescent artillery. Modernized ordnance received a second model designation after a slash, for example 152-мм пушка обр. 1910/30 гг. (152 mm gun M1910/30). In case of further modernizations of the piece, the intermediate modernizations were not reflected in the name, for example the later modernization was 152-мм пушка обр. 1910/34 гг. (152 mm gun M1910/34). Army designation versus factory designation After 1930, newly designed or constructed towed artillery received two official designations, the first of which was the traditional Army designation, e.g., 122-мм гаубица обр. 1938 г. (122 mm howitzer M1938), but another one was the index of a factory (or a developer: ordnance plants in the Soviet Union very