What are the three basic groups of parts in modern firearms?

The three basic groups of parts in modern firearms are indeed action, stock, and barrel.

The action is the core mechanism responsible for loading, firing, and ejecting cartridges. It is crucial because it contains the components that facilitate these operations, making it the heart of the firearm where most of the mechanical action occurs.

The stock provides the structural support necessary to stabilize the firearm while aiming and firing. It is essentially the part that is held by the shooter, allowing for control and positioning. A well-designed stock contributes to the overall feel and handling of the firearm.

The barrel is the tubular component through which the bullet travels when fired. The characteristics of the barrel, including length and rifling, directly influence the accuracy and range of the shot.

Together, these three components—action, stock, and barrel—form the fundamental structure of modern firearms, each playing a vital role in their operation and effectiveness.