CARTRIDGE CASE

• Cartridge case for small arms ammunition is also called shell and casing.  
• Shell are usually made of brass - 70% copper and 30% zinc.  
• 1. Rim: This is the part of the cartridge case serves to limit the forward travel of cartridge into the chamber and the clearance between the head and supporting surface of the bolt or breech block.
• Primer Pocket: This part has three functions: to hold the primer in a central position;  to prevent gas from escaping to the rear of the cartridge;   and to provide solid support for primer anvil.
• 1. Vent: Also called flash hole, this part provides a passage of heat and flame from the primer pocket towards the gunpowder chamber.
• Body: This is the ‘cork’ that plugs the breech to prevent gas from escaping at the rear of the gun barrel.  For bottleneck-shaped cartridges, the cork includes the shoulder and the neck.
• 1. Neck: This is the part that is occupied by the bullet, which is true for rifle and machine-gun cartridges
• 1. Cannelure: This is composed of serrated grooves found at the interior surface of the neck which has a dual function: to serve as lubricant groove and to prevent the bullet from being pushed or pulled.
• Crimp: This acts as the lip since it is found at the periphery of the mouth of the cartridge case.  It has also two functions: to aid in holding the bullet in place and to resist the initial forward motion of the bullet while the gunpowder undergoes combustion.
• 1. Shoulder: The part that supports the neck of the shell which is true to rifle and machine-gun cartridges.
• 1. Base: This is the bottom part of the case that contains the primer, rim (shell head), and headstamp.
• Headstamp:   The bottom surface of the shell that contains engraved data such as the manufacturer’s ID, caliber, and year of manufacture.
• 1. Extracting groove:  This is the circular groove near the base of the shell designed for automatic withdrawal after each firing.
• Straight case: This description of shell is true to pistol and revolver ammunition.  This is the casing of all rimmed-cartridges for revolvers and all center-fire pistol ammo that are now manufactured.
• Bottleneck case: This description is always true to rifle ammunition.  This is the casing of most modern center-fire rifle ammunition.  This is the type of shell that provides the greatest power capacity commensurate with over-all case length.
• Tapered case:  This is an obsolete type of case.  It is very rare but presently being used in magnum jet cartridge of caliber .22 firearms.
• crimping is the tightening of the mouth of the shell
• wad separates gunpowder and shots
• belt is the headspacer
• birdshot is te smallest shot
• buckshot is the largest shot with 9 shots
• the disc holds the priming mixture in place.
• alexander john forsyth is the father of percussion ignition
• percussion is the method of ignition of ammunition or cartridge case
• primer is the smallest component
• 3 types of primer are: boxer type and berdan type and battery cup type
• boxer type primer has separated anvil type
• boxer type is a reloadable type of primer
• anvil is part of the cartridge in berdan type primer
• berdan type is not a reloadable type of primer
• berdan tye has 2 or 3 flash hole
• battery cup type is a boxer type and is used for shotgun shells
• the parts of the primer are the primer cup, priming mixture, anvil and disc
• Col. edward boxer created the boxer type primer
• hiram berdan created the berdan type primer
• Bullet came from the word boulette which means little ball
• the primer cup contains the priming mixture
• anvil is a thin but rigid metal strip where the priming mixture is crushed once the firing pin strikes the primer cup
• primer pocket is the space at the center bottom of the shell
• the disc holds the priming mixture in place and prevents moisture