Which statement best describes single action firearms?

Single action firearms are designed in such a way that the hammer must be manually cocked before each shot can be fired. This means that after the shooter pulls the trigger, the firearm will not fire again until the hammer is re-cocked physically. This characteristic is pivotal in distinguishing single action firearms from other types, such as double action firearms, which can be fired by merely pulling the trigger.

While fully automatic firearms continuously fire rounds as long as the trigger is held, that functionality is not characteristic of single action firearms. Additionally, the mechanism where the hammer cocks and releases simultaneously with the trigger pull defines a double action firearm, not a single action. Regarding the limitation on the number of rounds, while single action firearms can have a restricted capacity depending on their design, this statement alone does not accurately define what single action means, as both single and double action firearms can have varied magazine capacities.

Therefore, the key point about single action firearms is the necessity of manually cocking the hammer before each discharge, which is why the statement about firing after manually cocking for each shot accurately describes their operation.