The firearm injuries are mechanical injuries (wounds) caused by projectiles (missiles) discharged from firearms.
The use of firearms, especially in criminal activities, appears to be increasing in many social surroundings.
Because of current high frequency of firearm injuries, physicians, both treating doctors and medicolegal experts, must have sufficient knowledge of characteristics of these wounds, in order to properly diagnose and treat them, as well as to adequately explain their forensic aspects in court. The rise of international terrorism has also made some knowledge of blast injuries desirable.
TYPES OF FIREARMS
Rifled weapons - comprise revolvers, "automatic" pistols, rifles and many types of military weapons.
They fire one projectile at a time through a barrel that has spiral grooves cut into the metal, which grip the bullet and impart a rotatory (gyroscopic) spin which assists in maintaining an accurate trajectory. In the revolver, a cylinder rotates under trigger pressure to line up a new cartridge. In older rifles, there is a bolt which has to be worked to bring a new round up from a magazine, whilst in self-loading and automatic weapons, gas pressure provides the energy.
The ammunition for rifled weapons comes in a great many sizes (e.g., calibre i.e. diameter of the projectile 6.35 mm, 7.62 mm, 7.65 mm, 9 mm). It is essentially a closed metal cylinder (cartridge) carrying the firing cap and propellant charge, into the distal end of which a single projectile is clamped. This may be lead or a lead core covered with a cupro-nickel, steel or other hard metal jacket. The propellant charge in modern firearms is no longer the old "black powder" which used to cause extensive soiling around wounds. Modern propellants consist of nitro-cellulose or other synthetic compounds.
Shotguns - are usually used for hunting. The smooth-bore weapon consists of a long metal barrel, and they often have two barrels, either side-by-side or "over and under". The open end of the barrel is the muzzle. They usually fire a large number of small spherical lead shot (pellets). A shotgun is designed for use up to about 30-50 m, and is unlikely to kill a man at its extreme range.
The cartridges for shotguns consist of a metal base containing a central detonating cap, supporting a cardboard or plastic tube. Inside this tube is the propellant charge, capped by "wad", that used to be made of felt, cork, cardboard, and nowadays is usually plastic. This wad acts as a piston for the overlying mass of lead shot. The open end of the cartridge is closed by a thin over-shot disc.
Discharging - On pulling the trigger, when detonated by the firing pin striking the cap, the propellant burns rapidly, producing huge volumes of gas which are further expanded by the very high temperatures of the ignition (explosion of gunpowder). The pressure of this gas propels...