If this is for big game hunting, you really do not need a whole lot of magnification for a 500yard shot. What you do need is a reliable way to either hold over with the reticle or dial the elevation with turrets.
I have a simple 280Rem boltgun, that is exceedingly accurate, so despite it being just a run of the mill rifle, I like to practice shooting at plates out to 600 yards with it.
The scope I have on it is a Variable Super Sniper 3-9x42. Although the magnification is not very high, the glass is very good and FFP reticle allows both easy holding over without regard for magnification setting, and ranging. Knobs also work superbly well.