The revolver has several advantages and unique features. Importantly, they are less expensive to manufacture, simpler in design, and more reliable in operation than semiautomatics. A revolver is easy to master, even for novices. Revolvers with fewer moving parts may be more accurate than semiautomatics. Rrevolvers are limited to six shots, are relatively slow to reload, the gap between barrel and cylinder makes them less efficient, and the trigger pull is greater. The anatomy of a representative double action revolver is shown below:
Barrel length is smaller for concealability and longer for accuracy or energy. The ejector rod under the barrel is used to eject fired cartridges before reloading. Sights on a revolver are usually a blade in the front and a notch on the rear. The frame is the largest part, and all other pieces attach to it. Frames are usually made of blued or plated steel, stainless steel, or lightweight alloys. A revolver may weigh less than 1 lb to more than 4 lbs. The cylinder contains five or six holes for the cartridges and can be swung out for easy reloading. This must be a conscious act, so that no empty cartridge cases will be found at a crime scene unless the assailant stopped to reload.
There is a gap between cylinder and barrel to allow the cylinder to turn freely, but this also allows gases to escape laterally, which at close range may deposit gunshot residue on surrounding structures and allow the forensic pathologist to reconstruct the scene. The lockwork translates the trigger pull to rotation of the cylinder, cocking and fall of the hammer. If this is done in one motion of pulling the trigger, it is termed "double-action." Single-action revolvers (old Colts of "cowboys") require manual cocking of the hammer before the trigger is pulled. Different types of grips are employed; larger grips allow more accuracy, smaller grips provide.