three things....you can shoot rifled slugs in your shotgun " as is" ...even with the full choke.
you can have your barrel cut off to 26" and install sights and have screw-in chokes installed for a smoothbore barrel...I believe there' s chokes with rifling in them that works fairly well.
or contact Hastings
http://www.hastingsbarrels.com/12guide.html
and see if they have a barrel for your gun.....there' s a very slim chance a browning barrel will fit it....but make them say so.