Which of the following is the most common action type in modern firearms?

Semi-automatic action is the most common action type in modern firearms due to its efficiency and ease of use. In a semi-automatic firearm, each pull of the trigger fires one round and automatically cycles the next round into the chamber from the magazine. This allows for relatively quick follow-up shots compared to other action types that may require manual operation between shots.

The semi-automatic design has become particularly popular in various types of firearms, including handguns and rifles, because it strikes a balance between rapid fire capability and control. This makes it suitable for a wide range of applications, from self-defense to competition shooting, which contributes to its prevalence.

The popularity of semi-automatic firearms is reflected in various settings, including recreational shooting and hunting, as well as in law enforcement and military use. This widespread use solidifies the semi-automatic action as a fundamental type recognized in the firearms community today.