Hi Brick,
I've seen numerous references to the La-5FN's range and it has been shown to be anywhere from 380 to 475. However, the most recent (an therefore accurate) data does place it just short of the 400 mile range. My guess is the Lavochkin was lucky to get that much. As was the case with most Soviet fighters, they were usually short ranged, since most activity was of a tactical nature. However, there were guite a few Yak-9D's and even some Yak-9DD's which were their long-range fighters.