Firearm mechanisms are the systems that enable a firearm to function. They include components like the trigger, hammer, and firing pin, which work together to ignite the ammunition. When the trigger is pulled, it releases the hammer, striking the firing pin and causing a round to fire. Different types of firearms, such as revolvers and semi-automatic pistols, have unique mechanisms. For instance, a revolver uses a rotating cylinder to hold multiple rounds, while a semi-automatic pistol automatically chambers a new round after each shot. Understanding these mechanisms is essential for safe and effective firearm use.