“Go and no-go” gauges were used to measure uniformity among gun parts. Notice the ridges and holes of the gauges. If gun parts fit snugly into their corresponding guage, then the part could “go” or be considered uniform. If not, then the part was a “no go” and not uniform. United States military inspectors used the gauges to help indicate interchangeability, a must-have arms criteria.

 

Interchangeability solved the logistical problem caused by broken one-of-a-kind guns, which needed repaired by a gunsmith. Because parts were mass-produced to create uniform, interchangeable parts, a carbine’s parts could be swapped.