Here's the most important component of long range shooting.... the person behind the trigger. It seems a fair number of people want to buy the rifle and not put in the trigger time.
Also, sight your rifle in for 300 yards and you have a fairly long distance for no hold over. It also makes things easier for 400 and 500 yard precision shots.
The best thing a person can do is take their big game rifle over on a prairie dog hunt and shoot at 350-600 yards. It will let you know what kind of windage and hold over is required. Then, when you feel confident you can try prairie dogs at longer distances.
Before the advent of fast twist barrels, range finders, low drag bullets and a lot of the current craze stuff I shot prairie dogs out to 550 yards with a bolt action .223 and the low BC 52 grain Speer HP. Just takes practice and knowing your firearm.
Now, back to throwing $$$$ at rifles and scopes.