If you have the model that comes drilled and tapped from the factory, H&R's standard Weaver base should work just fine. I am looking at the 10 gauge models myself, and was just on the factory website doing a little research; their scope mount, which according to what I read says it fits every firearm they currently make that is drilled and tapped for it. The mount comes with a hammer extension and costs $18 from their online store. Hope this helps a little :-)
Regards,
~.450Marlin~