What happens when the barrel latch of the M203 is depressed?

When the barrel latch of the M203 is depressed, the correct outcome is that it unlocks the barrel. This action allows for the safe removal of the barrel from the receiver, facilitating the loading or unloading of the grenade launcher. The design of the M203 includes this feature to ensure that the operator can quickly and efficiently change out barrels as needed for different missions or types of ammunition.

Understanding this mechanism is crucial for proper weapon maintenance and operation, as it enhances the user’s ability to operate the weapon effectively in various tactical situations. The other options do not accurately describe the function of the barrel latch. For example, securing the barrel would imply that it is being locked in place, while activating the firing mechanism or ejecting a cartridge are functions related to the trigger mechanism and operational cycle, not the barrel latch itself.