The barrel of a firearm has spiral cuts called rifling, which is made up of a series of lands and grooves. This allows the bullet to travel farther and with more accuracy.
Before the inclusion of rifling in the barrel of a firearm, a bullet comparison was accomplished by comparing the caliber of a projectile to a possible firearm manufacturer. The use of rifling in the barrels of firearms has not only improved accuracy and range, it has had the added benefit
of imparting macroscopic and microscopic markings onto the fired projectiles. The macro- scopic markings are easily seen with the naked eye and represent the lands and grooves in the barrel of the firearm. Lands are the raised portions of the barrel and are what remains of the original surface of the barrel before the grooves were formed. The grooves are the lowered spaces between the lands. These are some of the class characteristics that an examiner will use to determine if a particular class of weapon is involved in a case. The microscopic mark- ings represent the individual characteristics the examiner will use to determine if a particular weapon in the class fired the projectile. These are also known as striations on the bullet.