Bolt Action - A bolt is pulled back by the bolt handle to the cocked position prior to each shot.
Lever Action - A lever is used to cock the gun prior to each shot. There may be different locations of the lever depending on the design.
Break Action - This action is also referred to as hinge action. The gun is opened at a hinge point between the barrel and the stock to allow access to the loading breech.
Pump Action - The forearm of the stock is used to cock the gun by sliding it back toward the shooter. Returning the forearm to the forward position loads the next round of ammunition.
Semi-Auto Action - The firing cycle of a round also re-cocks the gun and feeds the next round into firing position awaiting the next trigger squeeze. This action is also referred to as self-cocking. A separate squeeze of the trigger is required to discharge the next round of ammunition.
Full Auto Action - Full auto incorporates the semi-auto cycle and adds the feature of continual shots as long as you keep the trigger depressed. You can empty your entire magazine just by holding the trigger in the squeezed position. This action is also called machine gun action.