What is the consequence of having too little headspace in a firearm?

Having too little headspace in a firearm can lead to increased case expansion and, in severe cases, potential explosion. Headspace is the distance measured from the chamber's face to a specific point on the cartridge when it is fully seated. If this measurement is insufficient, it can prevent the cartridge from being properly seated. As the gun is fired, the case can expand excessively under pressure. This abnormal expansion may result in the case becoming stuck in the chamber, which can ultimately lead to a dangerous situation, including the possibility of an explosion due to the inability to properly vent gases, or even a catastrophic failure of the firearm itself.

Moreover, this excessive expansion can cause damage to the firearm and poses significant safety risks to the shooter and bystanders. Therefore, maintaining proper headspace is critical for safety and proper firearm function.