I just picked up my first gun, a Savage FV-SR and a Bushnell .22 Rimfire scope. The scope came with the rings, which I believe are "Dovetail". It appears that the FV-SR has weaver or pickatinny rails pre-installed on it. Do I have to buy new rings? Is this something I can buy at Walmart? I live in a smaller town and would love to go shooting soon, rather than waiting for them to be mailed. Thanks!