Should i mount a scope on my marlin 30-30 rifle?

I would for a number of reasons. Unless you hunt exclusively in thickets, your hunting environment could change even on a single trip afield. You might find yourself having to shoot acorss a clearing. For years, a lot of critics wrote off the .30-30 as being little more than a 100 yard rifle for whitetail deer. In truth, it is an intermedicate range rifle, capable of producing clean kills between 150 to nearly 250 yards, depending upon the ammunition you are shooting through it. Most people, unless they have razor-sharp eyesight, can't shoot a rifle accurately enough with plain open sights much beyond 100 yards. And if you decided to shoot something such as a coyote at 200 yards, you would be lucky to get a well-placed shot in using just iron sights.