What is when a barrels bore is rifled what shape is its pattern of grooves?

When a barrel's bore is rifled, the pattern of grooves inside the barrel is typically spiral in nature. This spiral pattern is known as rifling, and it serves to impart a spin to the projectile as it travels down the barrel. This spin helps stabilize the projectile in flight, increasing accuracy and range. Rifling can come in different configurations, such as traditional lands and grooves, or more modern rifling patterns like polygonal or micro-groove rifling. The specific shape and configuration of the rifling will depend on the type of firearm and the intended use of the weapon.