I'm getting ready to order myself a new scope for my Ruger Mark 2 all-weather rifle in 7mm mag. When I purchased the rifle last year I bought a Tasco Mag IV scope for it. When I'm Hunting and target shooting at distances around 100yds or under, the scope seems to work pretty good. But past 100 yds I can start to notice that the optics are not very clear and that it won't hold the zero very well. What scope should I get that would work good out to 500+ yds and cost under $300. What about under $200? Thanks.