In relation to firearms, what does the term 'receiver' refer to?

The term 'receiver' refers specifically to the portion of a firearm that houses the operating parts and is often considered the core structure of the gun. This is where the serial number is found, as mandated by federal law, allowing for the identification of the firearm. The receiver typically includes components necessary for the firing mechanism, but its designation as the part that bears the serial number is crucial for legal and regulatory purposes, contributing to tracking and ownership records.

In contrast, the other options describe different parts of the firearm: the barrel is responsible for the projectile's trajectory; the part that holds ammunition would refer to either a magazine or chamber; and the trigger mechanism is integral to the firing process, allowing the shooter to discharge the firearm. By understanding the function and significance of the receiver, one can better comprehend firearm definitions and regulations.