What happens first when a blowback operated weapon is fired?

When a blowback operated weapon is fired, the first event that occurs is the ignition of the cartridge. When the firing pin strikes the primer in the cartridge, it ignites the gunpowder, resulting in an explosion that generates a high-pressure gas. This gas creates a force that propels the bullet down the barrel and also causes the bolt to begin moving backward due to the blowback action.

The sequence of events is crucial to understanding how blowback operated systems work. The explosion generates energy that drives the bolt to the rear, ejecting the spent cartridge and chambering a new round in subsequent steps of operation. This mechanism relies on the pressure created by the explosion to cycle the action effectively.

In contrast, the other choices describe processes that happen after the initial firing of the cartridge, thus missing the significance of the explosion as the first step in the firing sequence.