Yes, it's possible. Is it a good idea? That depends. If it has a cylinder bore because it's a mint trench gun with US markings you'd be crazy to fiddle with it. If it has a cylinder bore because somebody cut a standard barrel back to 18" and the finish is so-so anyway, go ahead.I have a model 12 Winchester with a cylinder bore barrel. Is it possible to put a choke of some type on it? Would appreciate any help.