Try e-gunparts.com
there is the Stevens side by side shotgun model 311
Generally, no. Barrel sets are individually fitted to the frame and will not just drop on. sales@countrygunsmith.net
The Stevens 311 is a double barrel shotgun.
Online
Try e-gunparts.com
100-300 USD
Numrich Arms has parts for the 311
hire it done.
Barrels have been cut down. 100-175 USD
100-300 USD
Possible special order.
Yellow pages category = GUNSMITHS.