Forensic Pathology for Police - Brainshare Public Online Library

Types of Weapons and Ammunition 341
to as “double-action.” Some double-action revolvers allow either single- or doubleaction
trigger pulls. Others are double-action only. Also of note with revolvers is the
gap that exists between the cylinder and the barrel. On discharge, a certain amount
of smoke is discharged from this “cylinder-barrel gap.” Figure 13.4 shows a closer
view of a revolver.
Fig. 13.4 A .357 revolver
Semi-automatic (self-loading) pistols: Semi-automatic handguns are frequently
mischaracterized by the media, as well as others, as “automatic” weapons. An automatic
firearm is a weapon that fires multiple times with a single pull of the trigger
and will continue to fire as long as the trigger is being pulled. Automatic weapons
cannot be sold or purchased within the United States unless special permits are
obtained. In contrast, a semi-automatic (or autoloading) firearm requires a separate
trigger pull for each discharge. The “semi-automatic” description applies to the selfloading
aspect of the firing mechanism. In a semi-automatic weapon, the discharge
provides enough energy to mechanically eject the spent (used) cartridge casing from
the weapon and insert a new, unspent cartridge into the firing chamber. In this
way, after a bullet is fired, the weapon is ready to fire again. Most semi-automatic
weapons have special devices (magazines) that contain multiple bullets, so that the
self-loading as described above can occur until all bullets contained within the
device are gone. In semi-automatic pistols, the magazines are typically contained
within the grip portion of the weapon. Figure 13.5 shows a semi-automatic pistol.
Miscellaneous handguns: There are a variety of non-revolver, non-semi automatic
handguns available. Many require the manual loading of a single cartridge, or
sometimes two (with two separate triggers and barrels) at a time. An example is the
derringer. Most of these have rifled barrels.
Handgun ammunition: A variety of ammunition types are available for handguns
(Disc Image 13.6). In general, the diameter of the bullet can be used to classify a
given bullet as either small, medium, or large caliber. Examples of small caliber
bullets include the .22 and the .25 ACP. Examples of medium caliber bullets include