A double action revolver is a type of firearm that can be fired in two ways: by pulling the trigger or by manually cocking the hammer. When the trigger is pulled, it both cocks the hammer and releases it, firing the bullet. This mechanism allows for quicker follow-up shots compared to single action revolvers, which require the hammer to be cocked before each shot. These revolvers typically hold six rounds in a rotating cylinder and are popular for their reliability and ease of use. Many law enforcement agencies and civilians choose double action revolvers for self-defense due to their straightforward operation and robust design.