100-1000 usd
The BL-22 was first introduced by Browning in 1970. It was made in Japan by Miroku and never was a Belgian Model. This was one of the first two popular Brownings that have always been made in Japan. The Citori is the other. The Auto 5 joined Japanese production in 1976. Retail price of a Grade I BL-22 in 1970 was $74.50 and 92.50 for a Grade II.
500-1000
A Browning BL-22 in that condition will bring 420 dollars for a Grade I rifle.If you have a Grade II,then 495 dollars.
You need the services of a professional appraiser
There were several different Browning models used as DU guns. Auto-5, A500, B-80, etc... Need to know exactly which model, and whether the supporting Ducks Unlimited paperwork is still with the gun, and so forth.
I would require a more detailed description of the shotgun in question,to include the chambering,the type of barrel(plain,matte rib,or vented) along with the overall condition of the shotgun.This is used to give you a more accurate value.
They never did. 14 ga was never made in any model by Browning
If this is still available, I would offer $1500.
What it's worth and what you can get are two different things. 200-2000 USD
Multiple thousands. How many depends on the specifics. Range of 2-10K
AFAIK, Browning never made a model 810.
Browning never made a model 306