If you use a standard Encore scope base (4.5 inches long, with 4 holes) on an Encore shotgun barrel, you can ruin it. The standard screws are too long and will push into the bore (see picture below). Most of the opinions say that T/C will NOT replace such a damaged barrel under warranty.
You must use a special T/C scope base Part# 9949 for Encore shotgun barrels. This special base is 8 inches long, with 6 holes. It uses the normal 4 scope holes and the 2 holes from the rear sight. The picture below shows the two bases and screws.
The correct length screws for an Encore shotgun barrel are .308 long, used with the #9949 base.
The standard, incorrect screws for an Encore shotgun barrel are .346 long, used with the #410 base.
The first picture was provided by DroptheHammer.
Beware of buying damaged barrels! DroptheHammer found his on GunBroker and I located mine on GunsAmerica.
This picture shows the two bases from above.