In order to successfully fire a pistol, what needs to be fully engaged?

To successfully fire a pistol, the trigger needs to be fully engaged. When the trigger is pulled, it releases the firing pin or striker, which then impacts the primer of the cartridge. This sequence is essential for igniting the gunpowder within the cartridge and, subsequently, firing the bullet. If the trigger is not fully engaged, the firing mechanism will not operate properly, and the pistol will not fire.

In contrast, while the safety mechanism is important for preventing accidental discharges, it must be disengaged or not engaged in a way that obstructs the trigger pull. The magazine is necessary to hold the ammunition but does not directly affect the firing. The slide is important for chambering a round and cycling through ammunition, but it does not replace the need for the trigger to be pulled to initiate a shot. Thus, the engagement of the trigger is the critical factor in the firing sequence of a pistol.