I have a DPMS Mark 12 in 556 that I have had for years and never shot / scoped. There's a lot of optics / scopes out there that I know nothing about. I would like to something that is a 2x10 variable power with illuminated retical (I think). Would like to stay around $500.00. Paying less is always nice. Would pay some more if I have to. Thoughts / suggestions? Thanks in advanced.