What component must be adjusted during the firing pin protrusion test?

The component that must be adjusted during the firing pin protrusion test is the self-locking screw. This screw is crucial because it controls the depth at which the firing pin protrudes from the bolt face. If the firing pin protrudes too far, it can lead to light strikes on the primer, potentially causing a failure to fire. Conversely, if it protrudes too little, it may not strike the primer with enough force to initiate ignition.

Adjusting the self-locking screw ensures that the firing pin is positioned correctly, thereby allowing for reliable ignition of the ammunition and ensuring the overall safety and functionality of the firearm during operation. The other components listed—barrel assembly, trigger mechanism, and pistol grip—while important for the firearm’s performance and handling, do not directly relate to the protrusion of the firing pin during this specific test.