Browning.com has sn data under customer service.
Beligum
You will have to call Browing with the sn to find out.
Belgium and Japan
What is the question?
The BAR Grade 1 Magnum is worth $600-800, depending on condition. Other grades of the same rifle sell for more (different finish, engraving) Excellent rifles.
It might be eaiser to ask who in Beligum didn't make a revolver.
By the serial number
It was made in 1946
50-1000 USD or so
100-10000 USD depending on specifics.
chocolate
50-500 usd