Which factor does not affect the trajectory of projectiles in Call For Fire?

The thickness of the barrel does not directly affect the trajectory of projectiles in a Call For Fire context. Instead, the trajectory is primarily influenced by factors such as the angle of fire, which determines the initial velocity and path of the round; weather conditions, which can alter air density and wind resistance; and the type of ammunition used, which can affect the projectile's weight, speed, and ballistic characteristics. While barrel thickness may play a role in overall weapon performance and durability, it does not fundamentally change the trajectory of the projectile once the round is fired.