There are some special types of bullets . It encloses the cartridge and also seals the breech after firing to prevent the gas from escaping. Smokeless powder produces 800 ml - 900 ml of gas per grain whereas black powder produces only 200 ml - 300 ml of gas per grain.Ĭasing is usually made from metal, paper or plastic. Previously black powder was used as propellant charge. It may be single base (nitrocellulose) or double base (nitrocellulose + nitroglycerine). Propellant charge is usually composed of smokeless powder. It contains either a mixture of mercury fulminate, potassium chloride and antimony sulphide or a mixture of antimony sulphide, lead styphnate, lead peroxide and barium nitrate or tetracene. It ignites when hit by a firing pin and in turn ignites the propellant charge. The primer is a pressure sensitive material contained within a cap. Some bullets may contain a metal jacket which is usually made of cupro-nickel, copper-zinc or steel. The projectile (bullets, shots etc.) is usually made from lead or lead-antimony alloy due to their high sectional density and malleability.
It prevents fouling of the barrel but tissue injury is limited due to almost no expansion or fragmentation of the bullet. Jacketed : They have a metal jacket over the lead core.But they cause massive tissue injury due to expansion and fragmentation in the wound. Non-jacketed : They are made of lead only and causes fouling of the barrel.They are usually called cartridges which is essentially a self-contained package of the primer, charge and bullet. Insides of a firearmĪ firearm has four essential components . Some similar weapons, but not technically firearms, are airguns, stud-guns etc. Other types of firearms include gyrojet guns (propellant charge contained in the bullet), paradox guns (shotgun with terminal rifling) etc. Their smaller barrel length limits their range and they are usually low powered than their bigger counterparts. Handguns : They are smaller versions of rifled firearms meant for easy carrying.It helps in acquiring the target easily by spreading the projectiles on a wider front at the cost of the range. They usually fire multiple small pellets at the same time. Shotguns : These are smooth bore firearms, meaning they don't have any rifling.It helps to increase accuracy and effective range by means of gyroscopic stability of the bullet. It helps in rotating the bullet very fast as it leaves the muzzle. Rifled firearms : This type of firearms has spiral grooves cut into the inside of the barrel called rifling.
There are three types of firearms that we need to be concerned about . Wound ballistics : This is the path of the bullet inside the human body if it hits one.External ballistics : This is the path of the bullet from leaving the muzzle to reaching its target.We will discuss it when talking about the inner workings of firearms. Internal ballistics : This is the path of the bullet before it leaves the muzzle.The movement of the projectile (aka the bullet) can be divided in three parts . To discuss it any further we need to understand the firearms first -Ī firearm is essentially a device that accelerates a projectile towards a target by means of energy generated from chemical reactions, usually a contained explosion. When we discuss firearms in Forensic Medicine we are mainly concerned about the effect of firearms on human bodies, especially the information that can be collected from a wound about the firearm used and the manner in which it has been used to aid in the judicial procedures.
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