The 2M-3 is a naval gun turret of Soviet origin. It was developed shortly after World War 2 to arm various smaller combat ships, submarines and civilian ships supporting the navy. The 25mm guns are unique to the Soviet navy and were not used on aircraft or land based applications.

The design is based on the earlier 25mm 84-KM autocannon. The locally controlled open roof mount is rather simple and is fitted with two 110-PM autocannon, with the one positioned above the other. The single operator is seated on the left of the mount, the two guns are located in the middle and the ammunition is stored on the right. Normally the mount is operated hydraulicly but manual control is fitted as backup. The guns are air cooled but cooled with a water hose during sustained fire.

The 110-PM autocannon fire the powerful 25x218mm round at a cyclic rate of fire of 450 rpm. The practical rate of fire is 270 to 300 rounds per minute. The 25mm rounds have a range of 2.5 km and may reach altitudes of 1.7 km. Since the weapons are manually aimed they are of little use against fast moving fighter aircraft.

The 2M-3 is fitted on a wide variety of small boats such as the Komar guided missile craft and the P-4 and P-6 motor torpedo boats. For only a few years the submarine mount was used on the Quebec, Whale, Whiskey and Zulu class submarines. In Chinese service they are used on the Hainan, Hoku, Huangfen, Lada and Shanghai classes as well as various mine warfare and auxiliary ships. In both Soviet and Chinese service newer classes were fitted with the larger and more powerful AK-230 turret.