All scope bases made for H&Rs are shown in the FAQs, the factory base is real popular, the Ironsighter is as well, I really like the Leupold base and for $7-$8 is hard to beat. The Weaver is popular if you want to mount a shotgun scope ahead of the hammer, but is a poor choice in comparison to the others due to the lost space at the rear of the base that hinders mounting a scope back far enough to clear the hammer which is critical. Choosing a scope that's Handi friendly is just as important, either a fixed power scope or a variable that has a small power ring and ocular bell that won't need high or extra high rings.
Tim