Of course, NO sights are mandatory. You could just point and the bullet would tend to go where you were pointing, right? Iron sights are an improvement on this -- peep sights are an improvement on open sights, except when it is dark or the game is running. Obviously you can hunt successfully with iron sights -- either open sights or peep sights. What you want to do is understand what a scope does for you and ask is the money worth the advantages provided by a scope?

First the DISadvantages of a scope. A scope adds weight (can be a disadvantage in terms of muscle strain and fatigue, can be a benefit in dampening out rifle recoil and steadying hold when taking a shot). A scope adds bulk which can get hung up on brush. A scope can become damaged and if you are depending on the scope, you are out of luck until the scope is fixed. Of course, the same can be said for iron sights, but I think iron sights may be less subject to damage and failure than scopes.

Now the advantages. A GOOD scope helps you target in limited light -- deep woods, twilight conditions at dawn and dusk, overcast days. A scope eases the task of aiming in that the quarry and the crosshairs are optically in the same plane and your eye doesn't have to change focus to align these properly to make the shot. The cross hairs are a more DEFINITE targeting mechanism than iron sights. The magnification of the scope again provides a more exact targeting ability.

If you are using a big game rifle, a cheap scope may not hold up very well. Imagine that shooting a rifle is somewhat akin to hitting the scope with a hammer along the long axis of the scope. The scope has to be a quality scope to hold up for very long. Cheap scopes are more prone to allowing moisture to penetrate -- water vapor, as on a humid day -- which will then fog when your scope cools.

My own thinking is that if you can afford a good scope, heck yes, buy the scope. You'll never regret it. On the other hand, if you have hunted for a long time with iron sights and are successful in the kind of hunting you do when using iron sights . . . maybe you are good to go with just iron sights.

If you should someday pickup some other kind of hunting, however, you might reconsider the scope. For example, if you deer hunt in the eastern woods with a .30-30 with open sights and find them entirely satisfactory for that kind of hunting, you might think about using a scoped rifle if you should ever go to Wyoming for a pronghorn antelope hunt or for an elk hunt.