AK-257


The AK-257 is a Soviet 57mm naval gun, originally a land ZIF-31 L/70 57mm cannon. During the early 1950s, development began of naval versions of the 57x348mmSR 70 calibre weapon which had entered service with the Soviet army in 1950 as the S-60. This was to be a supplementary weapon for larger warships and as the main gun armament for minesweepers and auxiliaries.
The twin gun version, ZIF-31, appears to have entered service with the Project 264 Minesweepers and the Project 310 submarine support ships in 1958. In 1960, two other versions of the mounting appeared; a single gun ZIF-71 for the modernised Skoryy class destroyers and the quad ZIF-75 for the Krupny/Kanin class destroyers. The ZIF designation is an industrial one and it is possible that the naval designations were AK-157, AK-257 and AK-457. In smaller warships these mountings were sometimes associated with MR-103 and in larger ones with the Yakhond radar. The ZIF-31/71/75 mountings may not have been very successful and an improved twin mounting appeared shortly afterwards as the AK-725. The twin 57mm ZIF-31 has also been manufactured in China as the Type 66 and there is a water-cooled derivative known as the Type 76. The AK-257 is currently employed on the Grisha class Corvette.