What purpose does a Go/No Go gauge serve?

A Go/No Go gauge is a critical tool used in firearms assembly to ensure that the headspace of a chamber is within acceptable limits. Headspace refers to the distance between the part of the chamber that stops forward motion of the cartridge and the face of the bolt when it is fully closed. Using a Go/No Go gauge allows gunsmiths and armorers to verify that the firearm is safe for operation.

When the Go gauge is inserted into the chamber and fits properly, it indicates that the headspace is acceptable, allowing the bolt to close without obstruction. Conversely, if the No Go gauge fits in the chamber when the bolt is closed, it indicates that the headspace is excessive and that the firearm may not function correctly or safely.

Other options mentioned do not pertain to the purpose of a Go/No Go gauge: measuring muzzle velocity involves ballistic analysis rather than chamber dimensions, determining magazine capacity relates to the number of rounds a magazine can hold rather than the chamber's specifications, and assessing barrel weight concerns the physical characteristics of the barrel, which is unrelated to headspace measurement. These functions are critical in ensuring firearm reliability and safety, distinctly demonstrating the role of the Go/No Go gauge in confirming appropriate headspace.