I have a Nikon prostaff 40 mm riflescope on my Ruger 10/22. I am thrilled with the scope and find it more useful than scopes that cost much more. It has excellent optics and is of very solid construction.
I wish Nikon would apply their optical expertise at making refractors for amatuer astronomers. If they did they would likely give us some reasonably priced scopes of excellent quality.