Bullet

Bullet is a round or elongated missile (as of lead) to be fired from a firearm[Merriam-Webster’s Dictionary].
The various class characteristics of bullets include caliber, number of lands and grooves, twist direction, and width of the lands and grooves. Individual characteristics of the bullet include the striation marks present on the bullet.
Class characteristics are always referred to the properties which can be associated only with a group and not with a single source. The following are the characteristic of bullets that can be classified under the class characters.
Number of Lands and Grooves
On discharging a gun, the grooves in the firearm's bore cause the bullet to spin as it travels through the length of the barrel. The high pressure created while propelling out the bullet causes the bullet to be pressed and scraped against the rifling. As a result, the fired bullet comprises the characters of the land and grooves.
Direction of Twist
The rifling present in the barrel is either twisted to the left or right, which in turn causes the bullet to rotate as it passes through the bore, which ensures gyroscopic stability in its flight.
Width of Lands and Grooves
It is a characteristic of a bullet defined as the distance between the two lands on the bullet.
Pitch and Depth of Lands and Grooves
Depth of the land and groove describes how deep the raised portion of the barrel is to the actual caliber of the firearm. On the other hand, the pitch is the angle of the groove edge concerning the width and steepness of the groove.
All these characteristics of a bullet are the ones that are imparted from a firearm onto the bullet.
Caliber
The caliber of the weapon is the diameter of the bore measured from land to land. This class character is also imparted during making the bullet [Forensic Yard].

Sources:

Bullet. Merriam-Webster’s Dictionary. Retrieved from: https://www.merriam-webster.com/dictionary/bullet

Class & Individual Characteristics of Bullet. Forensic Yard. Retrieved from: https://forensicyard.com/class-and-individual-characteristics-of-bullet/