If it is an option, the Elite series are really nice. Here is a link to the scope I put on my 50. I could not be more happy. It is really built like a tank.
http://www.bushnell.com/products/sco.../Product/?n=19
If there are any questions I can help with feel free to ask. There are some fine choices for scopes though. I like the SWFA, Nikon, and a couple of Millet models too.