Russian
57 mm/75 (2.24") AK-725 (ZIF-72)
Updated 15 February 2006
The problems with the 57 mm ZIF-31 and ZIF-71 mountings prompted the Navy in 1956 to issue a request for a completely new weapon system in this caliber.  The prototype was constructed in 1959 and by 1960 was going through proofing tests.  One of the problems noted during these tests was that the barrels had short lives, so new and improved barrels were designed which increased barrel life to over 750 rounds.  The mount was officially accepted into service in 1964 as the AK-725.

The AK-725 had twin water cooled ZIF-74 barrels, which were modified to use belt ammunition, thus allowing for longer firing periods before reloading.  Compared to the ZIF-71, this new weapon could fire bursts twice as long and had 80% less cooling time between bursts.  Each belt contains 550 rounds and the first round needs to be manually chambered.   The AK-725 was controlled by the ESP-72 fire control system, which was itself controlled by the MP-103 Bars radar.  In an emergency, the turret can be used manually via a simple optical gunsight.  This mount was in production from 1961 to 1988.

This weapon was not considered to be effective against anti-ship missiles, as was evidenced by a training accident in 1987 when a missile drone accidentally targeted the Small Missile Ship MussonMusson was firing its AK-725 mount right up until the moment of impact, but was unable to hit the missile.  The ship was destroyed by the resulting fire, with 39 crewmen killed.

The barrel was of monobloc construction with vertical blade type breech.  Recoil operated with water-cooled barrels.  Both barrels were mounted on a common cradle.  The turret itself is unarmored but was hermetically sealed with 6 mm (0.24 in) thick aluminum sides.

WNRussian_57mm-75_AK-725_pic.jpg

57 mm/75 AK-725 mount

WNRussian_57mm-75_AK-725_Turya_pic.jpg

Turya class patrol ship with an AK-725 mount on stern
Photograph from Jane's Warship Recognition Guide

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Gun Characteristics
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Designation 57 mm/75 (2.24") AK-725 (ZIF-72)
Ship Class Used On Moskva (Pr. 1123), Kresta I (Pr. 1134), Kresta II (Pr. 1134A), Nanuchka I (Pr. 1234), Poti (Pr. 204), Turya (Pr. 206M), Grisha (Pr. 1124), Ropucha (Pr. 775), Ivan Rogov (Pr. 1171) and Ugra (Pr. 1886) classes plus many others
Date Of Design 1958
Date In Service 1964
Gun Weight 610.68 lbs. (277 kg)
Gun Length oa 168.31 in (4.275 m)
Bore Length N/A
Rifling Length N/A
Grooves 16
Lands N/A
Twist N/A
Chamber Volume 92.15 in3 (1510 cm3)
Rate Of Fire 200 rounds per minute
Maximum burst length:  100 rounds per barrel
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Ammunition
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Type Fixed
Weight of Complete Round Tracer-FRAG - 14.0 lbs. (6.35 kg)
Projectile Types and Weights Tracer-FRAG - 6.17 lbs. (2.8 kg)
Bursting Charge Tracer-FRAG - 0.34 lbs. (0.153 kg)
Projectile Length N/A
Propellant Charge 2.65 lbs. (1.2 kg)
Cartridge - 4.92 lbs. (2.32 kg)
Muzzle Velocity 3,346 fps (1,020 mps)
Working Pressure 44,090 psi (3,100 kg/cm2)
Approximate Barrel Life over 750 rounds
Ammunition stowage per gun 550 round belts
Note:  Used the same ammunition as the Army's S-60 57 mm AA gun.
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Range
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Elevation With 6.17 lbs. (2.8 kg) Tracer-FRAGShell
Max Ballistic Range 9,210 yards (8,420 m)
Max Timer Range 7,600 yards (6,950 m)
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Mount / Turret Data
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Designation Enclosed Twin AA Mount AK-725
Weight  14.27 tons (14.5 mt)
Elevation -10 / +85 degrees
Elevation Rate 30 degrees per second
Train -200 / +200 degrees
Train Rate 35 degrees per second
Gun recoil 11.81 -14.57 in (30 -37 cm)
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Data from
"Entsiklopedia Otechestvennoi Artillerii" (Encyclopedia of Fatherland [Russian] Artillery) by A.V. Shirokorad
Special help from Vladimir Yakubov