What about 28mm? The Weaver rimfires are very nice scopes. I'd imagine they'd work with low rings. I have the 2.5-7x28 and really like it. The 4x is 28mm as well. Quite a bit more money than something like the Bushnell but quite a bit more scope as well and you're putting it on a really nice rifle.
Not necessarily recommending the seller, just using the link for illustration purposes.
http://swfa.com/Weaver-Classic-Rimfire-Scopes-C232.aspx 
