Which of the following is NOT a basic part of a modern firearm?

The correct answer indicates that the receiver is NOT considered a basic part of a modern firearm in the same fundamental way as the other components listed.

In the context of modern firearms, the basic parts often refer to the components that are essential for the firearm to function, which include the action, stock, and barrel. The action is responsible for loading, firing, and ejecting cartridges; the stock provides support and stability when aiming and shooting; and the barrel directs the bullet and may affect accuracy and range.

The receiver, on the other hand, is typically seen as the housing that contains the action and is a critical structural component rather than a basic functioning part like the others. Thus, while the receiver is an integral part of most firearms, it is not classified in the same fundamental way as the action, stock, or barrel when discussing the essential operational parts of a firearm.