For the rust take some WD-40 and some 0000 steel wool. gentally run the rust area reapplying WD-40 often. Go slow. Most rust is just surface rust and in many cases you can polish off most of the rust and retain most of the original blueing as well but remember this area will be suseptible to rust in the future as well so keep it well oiled.
Good news, good scope rings are pretty cheap now adays!!
As to your question about if super magnums are needed. Depends on what you want to do at these ranges.
500-600 yards is not that far out there with a modern center fire rifle round in an accurate rifle with todays modern big game bullets designed to perform at a wide range of velocities.
If your punching paper or slapping steel, no need for anything much over 6.5mm in caliber unless you want it or want to extend your range and shoot heavy higher BC bullets to help negate windage estimate errors.
For big game hunting, again, most modern centerfire rounds in a quality rifle are more then enough for this range of hunting.
When the range pushes past 800 yards and the game increases to over 400 lbs, then the larger magnums really shine on target. Maybe not as much as many would think ballistically but they certainly land on target with much more authority.
Kirby Allen(50)
