This gun was based upon the 84-KM which was designed in 1943-44. The specifications for a new weapon were first developed in 1945 and then modified in 1947. Trials started in 1949 and the gun was accepted into service in 1953 as 110-PM. Manufacturing in the USSR continued until 1984.

These guns were fed from 65-round belts and the early guns could also be fed by 7-round clips. The twin mount on which these guns were originally used was designated as 2M-3. At a later date, the mount was modified into 2M-3M version. In this later version, the automatics were converted to gas-operation and the firing rate was increased to 470 - 480 rounds per minute during trials. These guns were nominally rated as being air-cooled, but they were actually cooled with water from a special hose for at least 15 seconds during reloading.

At the same time as the 2M-3 mounting was being developed for surface ships, the 2M-8 wet mount was being developed for submarines. This mounting used the same 110-PM guns as did the 2M-3 but the guns were clip-fed instead of belt-fed. This version was accepted into service in 1954, but all guns were removed from submarines by the end of 1950s due to the changing nature of submarine warfare. The guns were kept in storage for a long time afterwards but were eventually scrapped.

In addition to the above mountings there were also several experimental mountings which did not enter service. The 2M-10 mount was an improved 2M-8 mount for submarines, but was not accepted into service. In parallel with 2M-3 mount, there was also a BL-130 mount under development. While the BL-130 had some advantages over the 2M-3 mounts, it was at a lower stage of readiness and rather then complete development it was decided to use the 2M-3 mount in its place. At the end of 1940, BL-120-I and BL-120-II mountings intended for the Stalingrad (Pr. 82) class battlecruisers were being designed. These were completely enclosed armored mounts. However, these ships were cancelled and the only two mounts completed (renamed 4M-120-I and 4M-120-II) were installed on the destroyer Neustrashimy (Pr. 41) for several years, until later replaced with 45 mm SM-20-ZIF mounts.

This weapon is produced in the PRC under the designation Type 61.

Actual bore diameter is 25.4 mm (1.0").

Data from:

• "The Naval Institute Guide to World Naval Weapon Systems 1991/92" by Norman Friedman
• "Jane's Ammunition Handbook: Ninth Edition 2000-2001" edited by Terry J. Gander and Charles Q. Cutshaw
• "Jane's Fighting Ships 1998-99" edited by Capt. Richard Sharpe, RN
• "Entsiklopedia Otechestvennoi Artillerii" (Encyclopedia of Fatherland [Russian] Artillery) by A.V. Shirokorad

Special help from Vladimir Yakubov