A gunsmith can help you.
700-1000
You can go to Browning.com and download a BAR manual.
Check the receiver carefully.
Best to ask a gunsmith for help.
Contact Browning Customer Service, and request an owner's manual for your rifle. You WILL need the pictures in it.
What do you want to know?
100-1000+ depending on specifics
500 USD
50-500 USD or more
DO NOT ATTEMPT THIS!!!!!!!!!!!!!!!! Send it back to Browning.
100-400 USD depending on condition.
Best to ask a gunsmith for assistance.