Good Question This is on the older Belgian barrels. "16" stands for the guage which is a 16ga. "65" stands for the length of the chamber. In this case: 65mm = 2 9/16"
Library.
No
if the gauge and chamber length are the same
Check the barrel and receiver.
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.
Nothing special.