The factory number 92 in March 1938 Artillery management issued the task of designing 95-mm tank gun. Grabin as usual working quickly, as early as September 38th, the administration sent a working draft of 95-mm tank gun F-39. Barrel consisted of casing and tubing. Shutter automatic vertical wedge. It was made two versions: the unitary (cartridge length 936 mm, in a T-28, he fed obliquely) and separate loading (shell length of 505 mm, 497 mm sleeve). Ballistics and ammunition were to coincide with the F-28 — 95-mm divisional gun (barrel length — 39 calibres.; Vertical aiming angle from -5 to +35 deg., Armor-piercing projectile weight — 13.3 kg, the initial velocity of the projectile — 630 m / s). Grabin, as usual, the approval of the project did not expect, and graduated from the drawings in advance and ordered a casting and forging.
Very first pre-production experienced tank HF 2 (different from the serial form and the dimensions of the tower guns and mask). In serial KV-2 tower had rounded sides
But he felt that the management of the Artillery wind blew in the direction of 107-mm divisional guns, cling Grabin groundwork for the F-28 and F-39 did not, and, having stopped work on 95-millimeter guns, began designing the 107-mm tank guns. Especially since it coincided with the eye on the tank guns of the Grabina. At least remember his words: "The tank wagon is for the gun." Grabin in 1940 with the project stands 107-mm tank gun F-42 has ballistics 107 — millimeter cannon reference 1910/30 years, and in April 41th, invited to do 45 days in the latest 107 — millimeter tank gun having ballistics newest divisional M-60. After only 77 days after it was the beginning of the design factory number 92 started issuing serial 107-mm tank gun ZIS-6. Tests ZIS-6 mounted on the KV-2 began in May 1941 Ballistics latest gun was a bit better than the ballistics of the M-60. ZIS-6 had a separate-case loading. The liner and shell served in a tray manually, their dosylka in the bolt due to the recoil energy is satisfied automatically.
It is clear that the tank KV-2 has a huge tower was suitable only for testing gun ZIS-6. Kotin Grabina fooled, saying the Central Committee that under the ZIS-6 tank will be ready when it's ready gun. When the war did about 800 guns, and Kotin, a reference to the manufacturing of pre-KV-2 did not even begin. In the end, all made guns go for scrap. In general, MN Svirin gives some other information on the number of issued guns:
Svirin MN Armour Shield Stalin. The history of Russian tank 1937-1943. — Moscow: Jauza, Penguin Books, 2006. — 448 p. — (Russian tanks). — 4000 copies. — ISBN 5-699-16243-7
According to the article by Alexander Shirokorad, the magazine "Arms and equipment"