The most successful and numerous use of the P-39 was by the Red Air Force (Военно-воздушные силы, Voenno-Vozdushnye Sily, VVS).
They received the considerably improved N and Q models via the Alaska-Siberia ferry route.
The tactical environment of the Eastern Front did not demand the high-altitude performance the RAF and AAF did.
The comparatively low-speed, low-altitude nature of most air combat on the Eastern Front suited the P-39's strengths: sturdy construction, reliable radio gear, and adequate firepower.

Soviet pilots appreciated the cannon-armed P-39 primarily for its air-to-air capability.
A common Western misconception is that the Bell fighters were used as ground attack aircraft.
This is because the Soviet term for the mission of the P-39, prikrytiye sukhoputnykh voysk (coverage of ground forces) is commonly translated ground support, which is often taken to mean close air support.
In Soviet usage, it has a broader meaning.
Soviet-operated P-39s did make strafing attacks, but it was "never a primary mission or strong suit for this aircraft".
The Soviets developed successful group aerial fighting tactics for the Bell fighters and scored a surprising number of aerial victories over a variety of German aircraft.
Soviet P-39s had no trouble dispatching Junkers Ju 87 Stukas or German twin-engine bombers and matched, and in some areas surpassed, early and mid-war Messerschmitt Bf 109s.
The usual nickname for the Airacobra in the VVS was Kobrushka ("little cobra") or Kobrastochka, a blend of Kobra and Lastochka (swallow), "dear little cobra".

The first Soviet Cobras had a 20 mm Hispano-Suiza cannon and two heavy Browning machine guns, synchronized and mounted in the nose.
Later, Cobras arrived with the M4 37 mm cannon and four machine guns, two synchronized and two wing-mounted. "
We immediately removed the wing machine guns, leaving one cannon and two machine guns," Golodnikov recalled later.
That modification improved roll rate by reducing rotational inertia.
Soviet airmen appreciated the M4 cannon with its powerful rounds and the reliable action but complained about the low rate of fire (three rounds per second) and inadequate ammunition storage (only 30 rounds).

The Soviets used the Airacobra primarily for air-to-air combat against a variety of German aircraft, including Bf 109s, Focke-Wulf Fw 190s, Ju 87s, and Ju 88s.
During the battle of Kuban River, VVS relied on P-39s much more than Spitfires and P-40s.
Aleksandr Pokryshkin, from 16.Gv.
IAP (16th Guards Fighter Aviation Regiment), claimed 20 victories in that campaign in a P-39.

The last plane shot down by the Luftwaffe was a Soviet P-39, on May 8 by  Oblt.
Fritz Stehle  of 2./JG 7  flying a Me 262 on Erzgebirge.

Also, the last Soviet air victory was in a P-39 on May 9 when Kapitan Vasily Pshenichikov scored against a Focke-Wulf Fw 189, in the sky over Prague.

Five of the 10 highest scoring Soviets aces logged the majority of their kills in P-39s.
Grigoriy Rechkalov scored 44 victories in Airacobras.
Pokryshkin scored 47 of his 59 victories in P-39s, making him the highest scoring P-39 fighter pilot of any nation, and the highest scoring Allied fighter pilot using an American fighter.
This does not include his 6 shared victories, at least  some of which  were achieved with the P-39.

The United States did not supply M80 armor-piercing rounds for the autocannons of Soviet P-39s—instead, the Soviets received 1,232,991 M54 high-explosive rounds, which they used primarily for air-to-air combat and against soft ground targets.
The VVS did not use the P-39 for tank-busting duties.

A total of 4,719 P-39s were sent to the Soviet Union, accounting for more than one-third of all U.S. and UK-supplied fighter aircraft in the VVS, and nearly half of all P-39 production.
Soviet Airacobra losses totalled 1,030 aircraft (49 in 1942, 305 in 1943, 486 in 1944 and 190 in 1945).

Airacobras served with the Soviet Air Forces as late as 1949, when two regiments were operating as part of the 16th Guards Fighter Aviation Division in the Belomorsky Military District.
The most successful and numerous use of the P-39 was by the Red Air Force (Военно-воздушные силы, Voenno-Vozdushnye Sily, VVS). They received the considerably improved N and Q models via the Alaska-Siberia ferry route. The tactical environment of the Eastern Front did not demand the high-altitude performance the RAF and AAF did. The comparatively low-speed, low-altitude nature of most air combat on the Eastern Front suited the P-39's strengths: sturdy construction, reliable radio gear, and adequate firepower.
Soviet pilots appreciated the cannon-armed P-39 primarily for its air-to-air capability. A common Western misconception is that the Bell fighters were used as ground attack aircraft. This is because the Soviet term for the mission of the P-39, prikrytiye sukhoputnykh voysk (coverage of ground forces) is commonly translated ground support, which is often taken to mean close air support. In Soviet usage, it has a broader meaning. Soviet-operated P-39s did make strafing attacks, but it was "never a primary mission or strong suit for this aircraft". The Soviets developed successful group aerial fighting tactics for the Bell fighters and scored a surprising number of aerial victories over a variety of German aircraft. Soviet P-39s had no trouble dispatching Junkers Ju 87 Stukas or German twin-engine bombers and matched, and in some areas surpassed, early and mid-war Messerschmitt Bf 109s. The usual nickname for the Airacobra in the VVS was Kobrushka ("little cobra") or Kobrastochka, a blend of Kobra and Lastochka (swallow), "dear little cobra".
The first Soviet Cobras had a 20 mm Hispano-Suiza cannon and two heavy Browning machine guns, synchronized and mounted in the nose. Later, Cobras arrived with the M4 37 mm cannon and four machine guns, two synchronized and two wing-mounted. "We immediately removed the wing machine guns, leaving one cannon and two machine guns," Golodnikov recalled later. That modification improved roll rate by reducing rotational inertia. Soviet airmen appreciated the M4 cannon with its powerful rounds and the reliable action but complained about the low rate of fire (three rounds per second) and inadequate ammunition storage (only 30 rounds).
The Soviets used the Airacobra primarily for air-to-air combat against a variety of German aircraft, including Bf 109s, Focke-Wulf Fw 190s, Ju 87s, and Ju 88s. During the battle of Kuban River, VVS relied on P-39s much more than Spitfires and P-40s. Aleksandr Pokryshkin, from 16.Gv.IAP (16th Guards Fighter Aviation Regiment), claimed 20 victories in that campaign in a P-39.
The last plane shot down by the Luftwaffe was a Soviet P-39, on May 8 by  Oblt. Fritz Stehle  of 2./JG 7  flying a Me 262 on Erzgebirge.
Also, the last Soviet air victory was in a P-39 on May 9 when Kapitan Vasily Pshenichikov scored against a Focke-Wulf Fw 189, in the sky over Prague.
Five of the 10 highest scoring Soviets aces logged the majority of their kills in P-39s. Grigoriy Rechkalov scored 44 victories in Airacobras. Pokryshkin scored 47 of his 59 victories in P-39s, making him the highest scoring P-39 fighter pilot of any nation, and the highest scoring Allied fighter pilot using an American fighter. This does not include his 6 shared victories, at least  some of which  were achieved with the P-39.
The United States did not supply M80 armor-piercing rounds for the autocannons of Soviet P-39s—instead, the Soviets received 1,232,991 M54 high-explosive rounds, which they used primarily for air-to-air combat and against soft ground targets. The VVS did not use the P-39 for tank-busting duties.
A total of 4,719 P-39s were sent to the Soviet Union, accounting for more than one-third of all U.S. and UK-supplied fighter aircraft in the VVS, and nearly half of all P-39 production. Soviet Airacobra losses totalled 1,030 aircraft (49 in 1942, 305 in 1943, 486 in 1944 and 190 in 1945).
Airacobras served with the Soviet Air Forces as late as 1949, when two regiments were operating as part of the 16th Guards Fighter Aviation Division in the Belomorsky Military District.
Bell P-39 Airacobra