Laurent, bonjour.
I have never seen Hartmann's Flugbuch, except one page on one of his biographies (by Schiffer).
However, let me suggest some kind of practice that I have seen both in RAF Forms 540 and RAF Logbooks and had done myself and seeing other pilots doing, whilst flying civilian aircrafts.
There is a tendency amongst some pilots to "round" the Hour (H) he sees on his clock to the highest or lowest decimal. I have seen on some RAF Logbooks entries for, for example 21:42hs, whilst on the RAF ORB it is registered 21:45hs and vice-versa...It is known that whilst cross-checking Logbooks versus Official Documents (Squadron Diaries), this may occur...
One would need, to verify if Hartmann "tended to round the hours", to have the JG 52 War Diary and cross-check with his Flugbuch.
Maybe other Historians can add a bit more about that and if they ever found such discrepancies between Logbooks and Squadron War Diaries....I guess they do exist quite a lot indeed.
Regarding the correct place of the combats...I GUESS (it is my humble opinion) that the pilots (all nationalities) tended to register an overall area where the combat ocurred...for instance when the combat started...or after achieving the victory and checking his whereabouts. During the "dogfight", I really doubt that the pilot would be preoccupied where he is going or not...he is only focused onto shooting down his opponent...This "general area" of combat can be seeing reported here, for example, amongst dozen of US Army Air Corps fighter pilots:
http://www.wwiiaircraftperformance.o...t-reports.html
So, returning to Hartmann's 39th claim....why not can it be considered his claim for a LAGG 3 with some 10-15 minutes of discrepancy and some 10-15 km of the Normandie-Niémen losses (3 losses you informed)?
Am not sure also, how the orders from above were issued to register the combat entries...The time recorded is the time the combat started or when the enemy crashed down (which I assume is the correct)?
Most humbly yours,
Adriano Baumgartner