When should a shooter never fire a succeeding round following a squib load?

The most appropriate choice is to never fire a succeeding round following a squib load after the barrel has been checked for obstructions by a line officer. A squib load occurs when a bullet is improperly loaded, resulting in a situation where the bullet may become lodged in the barrel, creating a potentially dangerous obstruction.

If a shooter does not check for a blockage caused by a squib load before firing another round, the next bullet can strike the obstruction and cause catastrophic failure of the firearm, potentially injuring the shooter or others nearby. The role of a line officer in this scenario is crucial, as they are trained to safely inspect firearms and ensure the environment is safe for shooting. After the barrel has been officially inspected and deemed clear, it becomes safe to fire again.

Other options, such as checking for visual signs of damage or firing under conditions of immediate threat, do not align with the safest protocol, as they may overlook the essential step of ensuring the barrel is clear of obstructions. Proper safety procedures dictate that only after thorough checks confirming the firearm's safe operation, overseen by a qualified individual, should shooting resume.