A little more info,
"Simultaneously (early spring 1942) a program for rearmament of Hurricanes with Soviet cannons and guns had been initiated, as calibre and fire power of the original British armament (up to twelve 7.62 mm Browning machine-guns) was considered too weak.
Two alternative replacements of four Browning machine-guns were proposed by the gun designer B.G.Shpital'nyj together with specialists of Zavod No.115 (co-located with Yakovlev's OKB) in Moscow:
1) four 20 mm ShVAK cannons, two 7.62 mm ShKAS machine-guns and six racks for RS-82 rockets, or
2) two 20 mm ShVAK cannons, two 12.7 mm UBK machine guns and six racks for RS-82 rockets.
After evaluation by NII VVS from 28 December 1941 to 3 January 1942 the first alternative was adopted.
Even before official conclusion 30 SAM of VVS SF replaced four Browning machine-guns with two 12.7 mm UBT and two 50 kg bombs as proposed by Boris Safonov in VVS SF. Armoured pilot seat backs were also installed.
The armament modifications were mainly made at Zavod No.81 in Monino, Zavod No. 89 in Gorkiy and in workshops of 6 IAK in Podlipki, but also in several frontal units (eg. VVS SF). A total of some 1.200 Hurricanes were re-equipped with Soviet armament.
Because of lack of spares for the Merlin Mk.XX engines installation of Soviet M-82A, M-88 or M-105 engines was studied, but this proposal was not adopted.
In spring 1942 VVS SF was in urgent need of light bombers, and 120 Hurricanes were modified to carry two under-wing mounted 100 kg bombs.
Because of the relatively big number of Hurricanes in VVS SF special two-seater training Hurricanes were considered necessary, and 10 aircraft were modified with a second cockpit and double command. In order to save weight eight of the twelve machine guns, the armoured seat back of the pilot etc. were dismounted. A number of two-seaters were also used without double command for courier purposes, and one two-seater was further modified as "ambulance" aircraft and used by 10 AE VVS SF.
Several two-seater Hurricanes were also used at the Glider Aviation School of Red Army Paratroop Forces (VAPSh VDV KA) in Saratov for towing Antonov A-7 and G-11 transport gliders, and a number of operational sorties were also performed.
Other Soviet Hurricane modifications included a tactical recce version with an AFA-I camera in rear fuselage (used eg. by 118 RAP SF and 3 GIAP KBF), experimental fixed and retractable ski-undercarriages etc.
In summer 1942 it became evident that Hurricanes were no match for Bf 109 "Filips", and the Hurricanes were gradually transferred to PVO-regiments in the Soviet rear. At least 26 GIAP (of 7 IAK, later 2 GIAK) of the PVO Army in Leningrad used Hurricanes as night fighters until spring 1944.
In autumn 1943 and early 1944 some 45 Hurricane Mk.IID and 30 Mk.IV intended for ground-fighting (equipped with 40 mm cannons) were delivered. Evaluation and conversion training showed clearly that cannon-equipped Hurricanes were inferior to Il-2s already in major production, and were thus not used for frontal sorties. On 1 July 1943 there were already 495 Hurricanes in PVO-regiments and 1 June 1944 the PVO-Hurricanes numbered 711.
One spectacular incident took place deep in the Soviet rear, when four Hurricanes of 1./933 IAP (of 144 IAD; piloted by st.lt. P.G.Dergachev, ml.lt. G.N.Sevastyanov, ml.lt. P.N.Grachev and ml.lt. N.A.Lopusov) strafed a Ju 290 A-9 (W.Nr. 110185, A3+CB) of 1./KG 200, which had landed in the Kalmykian steppes at night 22-23 May 1944. This aircraft had taken off from Zilistea in Romania, carrying some thirty Kalmykian "freedom fighters", with the task to assist the resistance movement in Kalmykia, recently recaptured after the German occupation (Unternehmen Salzsee).
Lend-lease fighter conversion training was mainly performed in various ZAPs (Reserve Aviation Regiments), of which the first was 27 ZAP in Kadnikov (Keg Ostrov) in the Arkhangelsk-Vologda region. 16 May 1942 6 ZAB (Reserve Aviation Brigade), comprising of 14 and 22 ZAP, was formed in Ivanovo, which become the main conversion training centre.
In the Ural Military District Hurricane conversion training was provided by 17 ZAP.
The first Soviet Hurricane downed by Finnish AF was BD761 piloted by st.lt. N.F.Repnikov, 152 IAP who crashed mid-air with Sgt. T.Tomminen, LeLv 28 in Morane-Saulnier MS.406 MS-329 at Karhumäki (Medvezhegorsk), Eastern Karelia on 4 December 1941, killing both pilots. For his "taran-victory" Repnikov was posthumously awarded the HSU 22.2.1943.
Several Hurricanes of the Karelian Front Air Forces were shot down by Finnish Air Force in 1942-
1943. Four force-landed Hurricanes (Z2585, Z3577, BM959 and BE559) were considered repairable, but ultimately only Z2585 (of 152 IAP, force-landed at Tuoppajärvi in early February 1942) was restored to flying condition in Finland. This aircraft became HC-452 in Finnish Air Force, and performed its first flight in Finnish colors on 13 October 1943."
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