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 (despite the fact that, at least initially, the metrication of artillery was "soft" rather than "hard" - artillery piece size was not switched to ‘round numbers’ such as 50 mm, 75 mm, 100 mm, 150 mm and so on). The measurements of artillery pieces inherited from Czarist Russia were converted into millimeters, and in some cases, part of the attributes was dropped; the fractional part of the metricized caliber measurements were rounded to the nearest integer value. Examples of these modified designations include 76-мм дивизионная пушка обр. 1902 г. (76 mm divisional gun M1902) or 152-мм пушка обр. 1910 года (152 mm gun M1910, former 6 inch siege gun M1910).
The industrial growth of the Soviet Union during the late 1920s and the 1930s allowed the modernization of older or obsolescent towed artillery, as well as the design and construction of new varieties of towed artillery. Modernized ordnance received ‘slashed’ model designations, e. g. 152-мм пушка обр. 1910/30 гг. (152 mm gun M1910/30). If the piece was modernized more than twice, the two digits of year of the later modernization were included into the official designation, e. g. 152-мм пушка обр. 1910/34 гг. (152 mm gun M1910/34). Newly designed or constructed towed artillery (after 1930) 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 was the index of the developer or producer (ordnance plants in the Soviet Union very often had their own design bureaus). This consisted of between one to three letters and the project number. For the 122 mm howitzer M1938 mentioned above, the developer index is M-30. Letters identified the developer or producer. For example, M stands for Motovilkha plant, B – for ‘Bolshevik’ plant, S – for Central Artillery Design Bureau, D – for Factory No. 9, ZiS – for Factory No. 92 named after Joseph Stalin and so on. There was one exception: the artillery plant named after Mikhail Kalinin; their project number was placed first, followed by the 'K' letter; examples of these designations include 61-K or 20K (variants with and without a dash are both widely used in historical documents). For some pieces of towed artillery, both the Army and developer names were well known and interchangeable such as the 76 mm divisional gun M1942 / ZiS-3; after the piece was proven in battle, the Army designation (became well known, was issued, or was predominantly used?). For some other guns such as the 45 mm anti-tank gun M1937, the developer index (53-K) was very rarely used even in popular literature of the time.
This system was used throughout all of the Second World War and for some time following. But in the 1950s, another change took place. In the official names of newly designed pieces, the M19XX (обр. 19ХХ г.) was dropped and the developer index took the place of it as the unique identifier, e. g. 122-мм гаубица Д-30 (122 mm howitzer D-30). But unlike the first naming change (metrication), old towed artillery pieces of the WW2 era were never renamed, e. g. in the official ballistic tables printed in 1968, the D-1 was still referenced as a 152 mm howitzer M1943, and not as a 152 mm howitzer D-1.
The third change was connected with introduction of the GRAU system of indices for ordnance, weapons, and munitions. After this introduction, the developer index was dropped from the official piece name (but it still officially exists through the design and testing process); henceforth, the GRAU designation was used as the unique identifier, e. g. 152-мм пушка 2А36 (152 mm gun 2A36). This is the current system used by the Russian Federation's Agency for Missiles and Artillery (known as GRAU) and the Russian Strategic Rocket Forces.