I inherited a .22 caliber Ruger Single Six that was my Father‘s. If memory serves me, when he bought it new it came with two cylinders, .22 long rifle and .22 mag, but maybe I‘m wrong. When it was shipped to me from Arizona, all I got was the .22 long rifle cylinder. Can I just buy a .22 mag cylinder, or is this an item that needs fitted by Ruger? Thanks.