In order for a bullet (even a round ball) to be stabilized it must be spun. The longer the bullet the faster it must spin top be stable. This spinning is called a gyroscopic effect. If the bullet is not stabilized it will simply fly downrange tumbling and spinning end over end. This tumbling creates huge ammounts of turbulance around the projectile causing it to loose velocity incredibly fast and causing it to veer off its intended course very irradically.

Spin is created two ways with a slug.

One is with a rifled slug where the slug has angular grooves molded onto the slug itself. These grooves spin the slug similar to the way a tire turns your vehicle. When friction is created in a direction other than the direction of travel that friction will turn (spin) the object in that direction.

The other way is to place a bullet inside a plastic sleeve called a sabot and fire it in a fully rifled barrel. The rifleing cuts grooves into the plastic sabot and spins the sabot. The sabot and bullet are pressed tightly together under pressure and the friction created between them holds them together and the sabot imparts spin to the bullet.

A smooth bore barrel will not fire sabot slugs with any accuracy and terminal performance will be a crap shoot as well since the bullet will be tumbeling when it reaches the animal.


A simple way of looking at it is to picture a football being thrown. The throw that spins the ball perfectly will always fly more accurately but he throw that caused the ball to tumble may get there and it may not.