Techsan-
Someone has refinished your Model 11 in nickel. It should be very durable, but it is not original.
jhp-jcp-
The ring you are describing is a friction ring. If the bevel is on the inside, you have a Browning A5 friction ring. Friction pieces are made of bronze with a spring steel band around the outside and are used under the friction ring when firing heavy loads. Do not fire the shotgun without friction pieces as it causes the barrel extension to bottom out in the receiver, possibly damaging it. You can use Browning A5 friction pieces. Numrich Arms has some parts for your shotgun.
http://www.e-gunparts.com/DisplayAd....U=55820-01&MC=