I'm just wondering about the difference between new and old model "extra" cylinders. I bought an old model single six with a .22 cylinder. My boss bought the same gun 3 weeks later with a .22 mag cylinder. I wnat a .22 mag cylinder, and noticed that his mag cylinder looks like a new model cylinder. Are new and old model cyliders interchangeable, or do all of the mag cylinders just look the same? Do I need to look for cylinders from the same year to find a replacement? Any help would be appreciated.