I can't help you with the drill and tapping ,but yes you can shoot slugs out of it .Use the Foster type.They are a soft lead and will shoot thru any choke without damaging the gun.Remington,Winchester,Breneke,all make the foster slugs,and they are all under $4 a box. At Wally world and other large stores they are closer to 3.50. Just try different brands and choose the one that shoots best in your gun.