The bullet / projectile must turn on itself to go straight and reach the target. To obtain a correct stability, bullet / projectile must have a minimum speed. The movement and the speed of rotation is determined by scratches in spirals which are inside the barrel along its entire length and which rotate about the axis thereof. Depending on the weapon the number ranges from 4 to 6. As mentioned in the "ammunition", between the percussion and the output of the projectile it happens about 5 milliseconds. During this time, the ball will follow scratching the barrel that will transmit a helical path and give it gyroscopic stability in the air. The bullet / projectile has a slightly larger diameter than the barrel so that it can enter into force, and take the form of stripes.

 

Therefore, the projectile must be soft enough to allow its deformation during its passage in the barrel and scratches from it, but strong enough to withstand high acceleration while shooting.

"That's why we find traces of the projectile. These serve to identify the weapons ballistics research during"

For more information see on the physical gyroscope and gyrostabilization.