I did some digging before on this, only combat I think the P-63s did was against Japan. I have a book on P-39 Aces and Soviet Aces, and could find no confirmation of P-63s "in combat" on the East Front before the war ended, only some sorties against the Japanese in August of 1945.
The P-39Qs were used prolifically on the East Front, and im sure any seen over Berlin were likely those.
I have seen nothing definitive yet on ETO combat for it, so far its rumours and anecdotal eye witness stuff, without confirmation of sources. The P-63 and P-39 look so similar, I really have my doubts about enemy combatants saying for sure they saw them, since flak gunners and pilots on both sides routinely misidentified fighters that had national insignia painted on them.
Colonel Pokryshkin was flying a P-39N in May 1945 "white 100", he was a 3 time winner of the Hero of the Soviet Union, the second highest Russian ace of the war, and had 59 kills, yet he isnt equipped with a P-63? This is a high scoring Guards fighter unit. They got the best personnel, booze, accolades and lots of press, yet the new P-63 is kept from them? I dunno.
In fact, I can find no evidence any of the top VVS P-39 aces or Guards Fighter Rgts like 16 GIAP and 100 GIAP were flying P-63s at wars end, which is kinda odd. Surely if it was available they would have been equipped with it?
Its no accident that Colonel Kozedub was flying an LA-7 at wars end. He didnt need to ask special to get them for his unit.
