Re: Budget 500 yard gun ?
+1 on what LongtimeLongranger said. Any fast and flat cartrige with mild recoil will do you just fine.
A 308 win is another good one, but youll want a scope with dials. the good thing about the 308 is that you can shoot it aot and practice getting your D.O.P.E. and that would come in hany when you step into more horsepower for longer ranges. I would say that the 25-06, .264 Win, 270WSM or Win, or 7mm Rem would work well useing only mill-dots also.