NURSING ANM AND GNM

Detailed explanation-1: -The raised portions of the rifling are known as lands and the recessed portions are known as grooves. When a weapon is fired, these lands and grooves cut into the bullet, putting spin on it as it travels through the barrel of a firearm. Because bullets have an oblong shape, spin is necessary for accurate flight.

Detailed explanation-2: -Striations, firing pin marks, and breechblock marks are all individual evidence. The direction of the twist, manufacturer, number of lands/grooves, caliber, etc. are all class evidence. The above three are the only individual evidence pieces.