Which of the following locking procedures of a double action revolver happens last?

The correct choice is that the bolt engages the notch before the hammer is fully cocked. In a double-action revolver, the sequence of operations is crucial for understanding how the mechanism works and performs reliably.

When the trigger is pulled back, several actions occur in succession. As the trigger is pulled, it first rotates the cylinder, allowing for the alignment of the next round with the barrel. During this time, as the cylinder rotates, the bolt will drop to allow this motion and will then rise to engage the notches of the cylinder at a specific point in the sequence. This engagement typically occurs when the cylinder is locked in place before the hammer is fully cocked.

Once the cylinder is securely locked by the bolt into the appropriate notch, the last stages involve the hammer falling, which is necessary for firing the round. The trigger reset occurs after the hammer falls, which prepares the firearm for the next shot. Therefore, the process of the bolt locking the cylinder occurs as a key step before the hammer is fully cocked and well before any reset functionality takes place. This order ensures safe operation and the mechanical integrity of the firing sequence within a double-action revolver.