if the gauge and chamber length are the same
No
Most of the Japanese made guns will interchange without fitting. On Belgian models, it is recommended that a qualified Gunsmith fit the barrel for you. Fitting is simply "the fine grinding of the metal" to make the barrel recoil back into the receiver smoothly.
Check the barrel and receiver.
Library.
Where will be marked on the barrel or receiver. When is 1977.
Follow the instructions in the A5 manual using the link below.
No
there are many avenues to find barrels for A5's. Try the "gunbroker.com" firearm barrel section. A5 barrels are sold there all the time.
50-500 usd
Browning.com has sn data under customer service. It will be marked on the barrel
If not marked on the barrel, take it to a gunsmith for testing.
How do you remove the breech block on a Browning A5 16ga shot gun