{{Russia-mil-stub}} {{Merge to|AZP S-60|discuss=Talk:AZP S-60#Merge proposal|date=March 2026}} {{no footnotes|date=November 2019}} {{Short description|Soviet 57 mm naval gun}}
thumb|right|ZIF-31 Naval AA Guns The '''AK-257''' is a Soviet 57mm naval gun, originally a land ZIF-31 L/70 57mm (Type 66/76) 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 (T58 class) and the Project 310 (Don class) submarine support ships in 1958.<ref>{{Cite web|title=Seagoing minesweeper - Project 264|url=http://russianships.info/eng/warships/project_264.htm|access-date=2020-12-10|website=russianships.info}}</ref> 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 (ZIF-71), AK-257 (ZIF-31) and AK-457 (ZIF-75). In smaller warships these mountings were sometimes associated with MR-103 and in larger ones with the Yakhond (Hawk Screech) 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.
==References== ===Citations=== {{reflist}}
===Sources=== {{refbegin}} *{{cite book | last = Koll | first = Christian | title = Soviet Cannon - A Comprehensive Study of Soviet Arms and Ammunition in Calibres 12.7mm to 57mm | publisher = Koll | date = 2009 | location = Austria | url = http://www.russianammo.org | isbn = 978-3-200-01445-9 | page = 472 }} * {{cite web |last=DiGiulian |first=Tony |date=February 27, 2017 |title=57 mm/78.7 (2.24") SM-24-ZIF | 57 mm/78.7 (2.24") ZIF-31 |url=http://www.navweaps.com/Weapons/WNRussian_57mm-78_zif-31.php |website=navweaps.com |location= |publisher=NavWeap |access-date=}} * {{cite web |last=DiGiulian |first=Tony |date=January 19, 2017 |title=57 mm/81 (2.24") ZIF-71 and ZIF-75 |url=http://www.navweaps.com/Weapons/WNRussian_57mm-81_zif-71.php |website=navweaps.com |location= |publisher=NavWeap |access-date=}} {{refend}}
Category:57 mm artillery Category:Naval guns of the Soviet Union Category:Arsenal Plant (Saint Petersburg) products