Chapter 2 Ammunition PDF

CHAPTER 2 AMMUNITION OBJECTIVES: To be knowledgeable in different types of ammunition To know the different parts of ammuni...

CHAPTER 2 AMMUNITION OBJECTIVES: To be knowledgeable in different types of ammunition To know the different parts of ammunition To know the importance of ammunition in ballistics A Brief History of Ammunition Introduction The first forms of ammunition consisted of loose powder, carried in a flask or horn, and various projectiles which were loaded into the barrel from the muzzle end. These early projectiles were often irregularly shaped stone balls or arrow- like objects. By the fifteenth century, ammunition had become fairly standardized and consisted of ‘black powder’ propellant (a mixture of charcoal, sulfur and potas- sium nitrate), followed by some wadding, a spherical lead ball and further wadding to retain it all in place. Materials other than lead had been used for the projectile, and it was recognized from an early period that the lighter the material, the higher the velocity. However, due to its ballistics properties and the ease of casting it into spheres or bullet- shaped projectiles, lead remained the preferred material. Early attempts at including the priming charge within the cartridge include the volcanic, lip, cup, teat, annular rim, needle, pinfire and rimfire systems. Most of these had a very short life span and, with the exception of the rimfire, only the pinfire attained any degree of popularity The pinfire was at its most popular between 1890 and 1910, and was still readily available on the continent until 1940. It had, however, fallen out of favour in the United Kingdom by 1914 and was virtually unobtainable by 1935. Calibres available for use in pinfire revolvers were 5, 7, 9, 12 and 15 mm, whilst shotgun ammunition in 9 mm, 12 bore and various other calibres was also available. Ballistics Page 1 Rim fire cartridge. The centre fire cartridge removed this limitation by providing a relatively soft cup containing the priming compound (the priming cap or ‘primer’) which was set into the centre of the base of a much stronger cartridge case. Although practical centre fire cartridges were available as early as 1852 in Britain, the final forms were not perfected until 1866 by Colonel Berdan (an American) and in 1867 by Colonel Boxer (an Englishman). These primer cap designs have never really been improved upon and are still in use today. Interestingly, Boxer-primed cartridge cases are normally used in American ammunition and Berdan in European ammunition A list of the dates of introduction for some of the more popular calibres of ammunition follows: Ballistics Page 2 Ballistics Page 3 Ammunition Components Basic terminology A round of ammunition. Generally refers to a single, live, unfired, cartridge comprising the missile, cartridge case, propellant and some form of primer. The term is also applied to live blank and tear-gas ammunition. The primer is basically the means for igniting the propellant. In rimfire ammunition, the explosive priming compound is spun into the hollow rim of the cartridge case. In centre fire ammunition, there is a small cup, called a primer cap, containing the priming compound. This priming cap is inserted into a recess in the centre of the cartridge case. In percussion weapons, there is a small cup, very similar to the primer cap, which contains the priming compound and fits onto a hollow nipple screwed into the breech end of the barrel. The propellant is a chemical or mixture of chemicals which, when ignited, produces a very large quantity of gas. This gas, when confined within a barrel and behind a missile, provides the propulsion to drive the missile down the bore and out of the barrel. A cartridge case refers to the ammunition case and primer and does not include the bullet. It can be either a ‘fired cartridge case’ or a ‘live cartridge case’. A live cartridge case has a live, unfired, primer, but there is no propellant or bullet present. A bullet refers to the missile alone. It can be either a ‘fired bullet’ or an ‘unfired bullet’. Pellets can be either the individual lead or steel balls found in shotgun ammu- nition, or the lead pellets for use in air weapons. ‘Lead slug’ is also sometimes used to describe air gun pellets, but this is not the correct term for this type of missile. Shot is another term for the lead or steel balls in shotgun ammunition, that is, ‘lead shot’. This is an acceptable alternative to ‘pellet’. Ballistics Page 4 Ammunition types TYPES DESCRIPTION SAMPLE Small arms -basically consists of a cartridge ammunition case, primer, propellant and some form of missile. There are really only three types of small arms ammu- nition in current production: ‘rimfire’, ‘centre fire’ and ‘caseless’. Rimfire -consists of a short brass tube, ammunition generally 0.22 in. in diam- eter, closed at one end. The tube contains a charge of propellant and has a bullet at the open end. The closed end of the tube is formed into a flat head with a hollow rim which contains the priming compound. Centre fire -ammunition is also generally ammunition made from brass, but the head is thick and heavy with a central recess or pocket for the primer cap. A hole leading from the primer pocket into the cartridge allows the flash from the priming compound to reach the propellant thus igniting it. -Consists of a bullet with the Caseless propellant formed around the ammunition bullet as a single solid piece, and there is no cartridge case. The primer is generally located at the rear of the propellant and is not enclosed in any metallic cup. Blank is exactly the same as bulleted ammunition ammunition except for the omission of the missile. In blank ammunition, the case mouth is sealed by either crimping the metal or inserting a wax plug or paper disc. Ballistics Page 5  Tear-gas cartridges are the same as blank ammunition except they contain a small quantity of a lachrymatory/sternutatory substance which is either chlora- cetophenone (CN) gas or o-chlorobenzalmalonitrile (CS) gas. Power tool, nail driving or stud gun cartridges are very similar to blank and tear-gas ammunition, and it is quite easy to mistake one for the other. In general, they are 0.22, 0.25, 0.32 or occasionally 0.38 calibre. The mouth of the car- tridge case is either rolled over onto a card disc or crimped. A colour-coding system, either coloured lacquer over the crimp or a coloured disc, is used to designate the strength of the cartridge. Grenade launcher cartridges are only encountered in military rifle calibres and, as the name indicates, are designed for the discharge of a grenade from a normal service rifle. The case mouth is invariably crimped, and some colour code, for example, the case painted black, distinguishes this type of cartridge from standard blank ammunition. Dummy cartridges have neither primer nor powder and are only used for weapon functioning tests or for practising the safe loading and unloading of weapons. These cartridges are normally chromium-plated or painted a silver colour. Snap caps are for the practice of firing a weapon without damaging the firing pin and lock mechanism by firing it without a cartridge case in place. This is generally called ‘dry firing’. Snap caps usually have a piece of rubber or hard plastic in place of the primer, and the case is chromium- or nickel-plated for identification purposes. Primer cap types In rimfire ammunition, the firing pin crushes the soft hollow rim of the cartridge against the rear of the barrel to explode the priming compound. In centre fire ammunition, the priming compound is held in a cup in the base of the cartridge case. Merely striking the base of the cup with a firing pin would do little more than dislodge the priming compound from the cup. An anvil has to be provided for the priming compound to be crushed against by the impact of the firing pin. In modern ammunition, there are basically three ways in which this is achieved. These are called the Boxer, Berdan or battery cup priming system. Ballistics Page 6 The Boxer primer was developed in 1866 by Colonel Boxer of the Laboratory at the Royal Woolwich Arsenal, England. In this type of primer, the anvil is a small bent disc of steel which fits into the cup making the primer completely self- contained. The flash hole in the cartridge case is centrally located and as it is of a relatively large diameter (approximately 1.5 mm in pistol ammunition), it is thus quite easy to push out the fired cup with a thin rod for reloading pur- poses. Boxer-primed ammunition is almost exclusively used in commercial ammunition The battery cup system consists of a plain cup with no anvil, which fits into a slightly larger inverted flanged cup containing its own anvil. The flanged cup provides a rigid support for the primer cup and anvil. This self-contained assembly fits into a recessed pocket in the base of the cartridge case. Battery cup primers are used exclusively in shotgun ammunition Cartridge cases In the Western world, these are almost invariably made of brass with a 75 : 25 copper/zinc alloy. Other materials including steel and plastic have been used, but not on any commercial basis. Aluminium-cased pistol ammunition has recently acquired some commercial success due to the cost saving of aluminium over brass. There are, however, a number of disadvantages. These include being non-reloadable and less robust than their brass counterparts. For large-scale users who do not wish to reload their empty cartridge cases or are firing for purely training purposes, the savings can, however, be very considerable and far outweigh the disadvantages. Cartridge case types Cartridge cases generally come in one of three shapes: 1. Straight cased, where the case diameter is approximately the same along its length. 2. Bottle-necked, where a wide-bodied case is, just before the case mouth, reduced in diameter to that of the bullet. This permits a very much larger volume of propellant to be used, and consequently higher velocities to be obtained, than in straight-sided cases. Ballistics Page 7  3. Tapered case, where a wide-based cartridge case is gradually reduced in diameter along its length. These tend to be in old European sporting rifle calibres and are seldom encountered. The cartridge case can be subdivided further into five categories according to the configuration of its base Various cartridge case forms Parts of a cartridge case applicable to all forms. (i) Rimmed. These have a flange at the base which is larger than the diameter of the body of the cartridge case. This flange is to enable the cartridge to be extracted from the weapon in which it is used. When describing rifle ammunition and the metric method of designating the ammunition is used, these are often identified by an ‘R’ after the case length measurement, that is, 7 57 mmR. The vast majority of revolvers are designed for use with rimmed ammunition. (ii) Semi-rimmed. These have a flange which is slightly larger than the diameter of the cartridge case and a groove around the case body just in front of the flange. When describing rifle ammunition and the metric system is used, these are identified by ‘SR’ in the cartridge designation. (iii) Rimless. In these, the flange diameter is the same as the case body and there is, for extraction purposes, a groove around the case body just in front of the flange. There is generally no letter system to designate this cartridge base type. Self-loading pistols are almost invariably designed for use with semi- rimmed or rimless ammunition. (iv) Rebated. This has an extractor flange which is less than the diameter of the cartridge case. The designation used in the metric system is ‘RB’. This type of cartridge case configuration tends to be reserved for high-powered cannon ammunition. (v) Belted case. These have a pronounced raised belt encircling the base of the cartridge. This belt is for additional strength in high-pressure cartridges. The metric designation is ‘B’. This type of cartridge case is generally only found in very high-powered rifle cartridges or military cannon ammunition. Ballistics Page 8 Shotgun ammunition Shotgun ammunition is once again a confusing subject with the smaller calibres being referred to by the approximate bore diameter, that is, 0.22 , 9 mm, 0.410. Once past 0.410 , the calibre changes to a ‘bore’ (or if using the American nomenclature ‘gauge’) size where the bore is the number of lead balls of the same diameter as the inside of the barrel which weighs 1 lb. Thus, a 12-bore shotgun has a barrel diameter of 0.729 and 12 round lead balls of 0.729 diameter weigh exactly 1 lb. It should be pointed out here that the ‘bore’ size when dealing with shotguns is different from the bore size of rifled weapons. In rifled weapons, the bore size is the diameter measured across the tops of the rifling lands Bore size, diameter of bore and weight of lead ball. Shotgun cartridge A. Over/undershot card B. Overcharge card C. Wad column D. Base wad E. Shot column F. Rollover crimp G. Felt cushion wads Ballistics Page 9 Size of pellets in shotgun ammunition The missiles used in shotgun cartridges can vary from a single ball or cylinder of lead of the same diameter as the bore down to pellets so small they are referred to as ‘dust shot’. As each country has its own method of nomenclature for these shot sizes, the matter can be quite confusing. The pellets used in shotgun cartridges have traditionally been made of lead with a small amount of antimony to increase their hardness. Lead accumulation in wildfowl has prompted the use of other materials, the most common being: soft steel, usually with a copper coating; bismuth, a heavy metal often alloyed with iron; tungsten, a very heavy metal often alloyed with iron. Shot sizes, weights and equivalent sizes (various countries). Shotgun slugs A shotgun slug is a single projectile primarily designed to be fired from a smooth- bored shotgun. Shotgun slug ammunition is available in most of the common shotgun calibres. The simplest form of slug is a round ball (sometimes referred to in the United States as a pumpkin ball or pumpkin shot). Since it is a symmetrical projectile, it will not significantly deviate from its intended path if it begins to spin due to air pressure. However, a smooth-bored shotgun firing a round ball is essentially a musket with its Ballistics Page 10 The original Brenneke slug - overcame these problems via the use of a solid lead, pre-rifled projectile with an attached plastic, felt or cellulose fibre wad. The wad provides drag stabilization by moving the centre of mass forwards. Foster slug This was basically a short round-nosed bullet with a deep cup in the base. Foster slugs are also made with rifling-type grooves cast into the outside of the missile. Saboted slugs Are sub-calibre missiles which have a discarding plastic collar surrounding the missile to bring it up to standard calibre. They are generally designed to be fired from a special rifled shotgun barrel to spin stabilize the missile. Reference: Firearm and Ballistics by B, J Heard Video Link: https://youtu.be/7GVTV6oA6fk https://youtu.be/EHCmibM3CWs https://youtu.be/6F3zJpwX6Og Ballistics Page 11