Hi all. I am buying a Single Six from a friend. He bought it long ago. It has a 5.5" barrel, driftable rear sight and is numbered 378XXX. It only has the magnum cylinder, which is numbered to the gun. The only markings are 22 cal Single Six. Should there be a 22 LR cylinder with this gun? Can I get one if I want one? It is a three screw model. Is that a good thing? There is no box and it needs a good deep cleaning. Thanks.