Reliable Redfield rings for use with 1"-diameter scopes on small-caliber rimfire rifles. These matte black rings fit standard 7/8" Weaver-style bases. Available: Medium, High.
I have a Nikon Prostaff Rimfire scope. It is 40mm. You will need the "HIGH" mount to use on these rifles. Once installed it fits perfect. Fits within a few millimeters of the barrell giving you the flattest fit you can expect. The "MED" mount is just a little short. Medium will work for 36mm or smaller scopes. But I am sure most people with a 17hmr will use 40mm or larger for light capture considering these are "varmint" rifles.