I've been using sightrons on my rimfire rifles for over a decade now. 36x's for br work and their 6-24's for silhouette's.
Attachment 200866

I sold off all my leupolds and switched over to sightrons and have never looked back. The sightrons are clear, the adjustments are positive and repeatible and the bodies on the scopes are long. Which is a good thing, it makes setting them up easy and there's no crawling the stock to see thru the scope like what happens with a lot of the short bodied scopes.

Been using the sightron sII series target scopes for 10+ years now on anything from rimfires to 308's:
2 36x
1 24x
1 6-18x
2 6-24x

I'm sure there are better scopes out there but any of these scopes will easily fit into your $500 price range.