The rifle was designed with the old pre-WW I combat idea in mind: Shoot accurately for a long distance, and keep your soldiers out of danger. That’s why the Carcano bullet was so long, so it would go a long distance without tumbling. But, they finally realized that most people can’t hit anything as far away as 1,500 meters.

Now the modern theory is to shoot a lot of bullets at closer range. Hit ‘em with a barrage of a lot of bullets from a rapidly-repeating rifle.

Oswald’s rifle was of the old type and thus it was very accurate. His telescopic sight wasn’t very good, but he could have used the “iron sight”, the rifle’s regular sight. Also, he might not have been aiming at the head. He was taught in the Marines to aim at the center of the silhouette, then the bullet could be as much as 18 inches off target and still score a hit. But everyone jumped to the conclusion that since he hit the head, he must have been aiming at the head. But if he had accidentally hit the heart, everyone would have assumed that he was aiming at the heart.