Can a 12 gauge Glenfield Model 778 shotgun be fitted with a slug barrel?

Answer the glenfield by marlin is compatible with marlin 120 12ga barrels are available for the 120 the only difference is the stocks wich are also interchangable the 120 is higher quality I love my glenfieldThat model is obsolete and you are not going to find a slug barrel. If you must use slugs, you can have the existing barrel modified to accept interchangeable choke tubes and use a rifled tube when shooting slugs.