Just got this gun from my FIL for free. The action was pretty stiff and wouldn't cycle. Stripped it all down and Frog Lubed the crap out of it. Runs slick as snot now. The wood is decent but does have a chunk missing from the right side up at the receiver. I'm thinking about doing something with the furniture and turning it into a cheap 3 gun shotgun. I haven't competed in 3 gun but I do compete in USPSA and other pistol games. I already have the pistol and rifle. What furniture will fit on this gun? Is there any chance of adding an extension tube? It has an accuchoke that I might cut off. Would I need to have the barrel threaded for a choke or just run it open? My understanding is the gun is actually a Hi Standard that was made sometime in the 60s/70s.