F - 34 tank gun The 76 mm tank gun M1940 F - 34 ( " 76 - мм танковая пушка обр . 1940 г . Ф - 34 " ) was a 76 . 2 mm Soviet tank gun used on the T - 34 / 76 tank . A modified version of the gun , the 76 mm tank gun M1941 ZiS - 5 ( " 76 - мм танковая пушка обр . 1941 г . ЗиС - 5 " ) , was used on KV - 1 tanks during World War II . Nowadays , the two versions are often referred to just by their factory designations , as " F - 34 " and " ZiS - 5 " , respectively . The F - 34 was designed before the start of World War II by P . Muraviev of Vasiliy Grabin ' s design bureau at Factory No . 92 in Gorky . The gun was superior to both contemporary 76 . 2 mm guns , Gorky ' s F - 32 and the Leningrad Kirov Factory ' s L - 11 , but it was the latter that had already been approved for the new T - 34 medium tank . The initial T - 34 Model 1940 with L - 11 was in production when Germany invaded the Soviet Union . The F - 34 was ready for production , but Marshal Grigory Kulik ' s high - handed interference with tank appropriation had made the relevant bureaucrats too frightened to approve the better gun . Grabin and the director of the Kharkov Locomotive Factory ( KhPZ ) , the centre of T - 34 production , conspired to produce the F - 34 anyway , and began to install the gun on new tanks . The new T - 34 Model 1941 tanks , which were issued mostly to company and platoon commanders , were immensely popular with their crews . Letters from tank units reached Stalin ' s State Defence Committee ( GKO ) , which officially authorized production . Also , due to Kulik ' s meddling , the KV - 1 heavy tank model 1940 had ended up mounting Grabin ' s older F - 32 gun , more poorly - armed than the T - 34 medium tank . Chief Designer of Tanks Joseph Kotin convinced the GKO to allow the use of the F - 34 gun on the KV - 1 heavy tank Model 1941 . The ZiS - 5 was a version of the gun designed to better fit the KV - 1 ' s turret . In 1943 , the thick armor of the new German Tiger and Panther tank s had rendered the F - 34 gun obsolete , and experiments were conducted to find a replacement . The better - penetrating 57 mm ZiS - 2 high velocity antitank gun was installed on some T - 34 / 57 tanks , but the smaller - bored gun couldn ' t fire an adequate high explosive round for general use . A more heavily - armoured T - 34 prototype was built , the T - 43 , but it was still vulnerable to the Tiger ' s 88 , and its mobility suffered too much from the weight of armour . In the end , the F - 34 was replaced by the D - 5T and ZiS - S - 53 85 mm calibre guns on the T - 34 - 85 tank , and by 122mm and 152 mm guns in the new IS - 2 heavy tank s and in tank destroyer s . Some F - 34 guns were also installed in Lend - Lease M4A2 Sherman tank s , known as the M4M , but there was no need for this conversion as U . S . 75 mm ammunition was in good supply ( Zaloga 1984 : 217 ) . Comparison of guns . The L - 11 gun was mounted on the initial T - 34 Model 1940 medium tank and the KV - 1 Model 1939 heavy tank . The F - 32 was on the KV - 1 Model 1940 . Subsequent models of both tanks mounted the F - 34 until it was replaced by 85mm guns in the T - 34 - 85 medium tank and KV - 85 heavy tank .