Abullet is akinetic projectile, a component offirearmammunition that isshot from agun barrel. They are made of a variety of materials, such ascopper,lead,steel,polymer,rubber and evenwax; and are made in various shapes and constructions (depending on the intended applications), including specialized functions such ashunting,target shooting, training, and combat. Bullets are often tapered, making them moreaerodynamic. Bullet size is expressed by weight and diameter (referred to as "caliber") in both imperial and metric measurement systems.[1] Bullets do not normally containexplosives[2] but strike or damage the intended target by transferringkinetic energy upon impact andpenetration.
The termbullet is from Early French, originating as thediminutive of the wordboulle (boullet), which means "small ball".[3] Bullets are available singly (as inmuzzle-loading andcap and ball firearms)[4] but are more often packaged with propellant as acartridge ("round" of ammunition) consisting of thebullet (i.e., the projectile),[5] thecase (which holds everything together), thepropellant (which provides the majority of the energy to launch the projectile), and theprimer (which ignites the propellant). Cartridges, in turn, may be held in amagazine, aclip, or abelt (for rapid-fireautomatic firearms). Although the wordbullet is often used in colloquial language to refer to a cartridge round, a bullet isnot a cartridge but rather a component of one.[6] This use of the termbullet (when intending to describe a cartridge) often leads to confusion when a cartridge and all its components are specifically being referenced.
The sound of gunfire (i.e. the "muzzle report") is often accompanied with a loudbullwhip-like crack as thesupersonic bullet pierces through the air, creating asonic boom. Bullet speeds at various stages of flight depend on intrinsic factors such assectional density, aerodynamic profile andballistic coefficient, as well as extrinsic factors such asbarometric pressure, humidity, air temperature and wind speed.[7][8]Subsonic cartridges fire bullets slower than the speed of sound, so there are no sonic booms. This means that a subsonic cartridge, such as.45 ACP, can be substantially quieter than a supersonic cartridge, such as the.223 Remington, even without the use of asuppressor.[9]
Bullets used in many cartridges are fired atmuzzle velocities faster than thespeed of sound[10][11]—about 343 metres per second (1,130 ft/s) in dry air at 20 °C (68 °F)—and thus can travel substantial distances to their targets before any nearby observers hear the sound of the shots.
Rifle bullets, such as that of aRemington 223 firing lightweight varmint projectiles from a 24 inches (610 mm) barrel, leave the muzzle at speeds of up to 4,390 kilometres per hour (2,730 mph). A bullet from a 9 mmLuger handgun, reaches speeds of only 2,200 kilometres per hour (1,370 mph). Similarly, anAK-47, has a muzzle velocity of about 2,580 kilometres per hour (1,600 mph).[12]
Round shot from the 16th centuryMary Rose Englishwarship, showing both stone and iron ball shot
The first true gun evolved in China from the fire lance (a bamboo tube that fired porcelain shrapnel) with the invention of the metal hand cannon sometime around 1288, which theYuan dynasty used to win a decisive victory against Mongolian rebels. The artillerycannon appeared in 1326 and the Europeanhand cannon in 1364. Early projectiles were made of stone. Eventually it was discovered that stone would not penetrate stone fortifications, which led to the use of denser materials as projectiles. Hand cannon projectiles developed in a similar manner. The first recorded instance of a metal ball from a hand cannon penetrating armor was in 1425.[13] Shot retrieved from the wreck of theMary Rose (sunk in 1545, raised in 1982) are of different sizes, and some are stone while others are cast iron.[14]
The development of the handculverin andmatchlockarquebus brought about the use ofcast lead balls as projectiles. The original roundmusket ball was smaller than the bore of the barrel. At first it was loaded into the barrel just resting upon the powder. Later, some sort of material was used as awadding between the ball and the powder as well as over the ball to keep it in place,[15] it held the bullet firmly in the barrel and against the powder. (Bullets not firmly set on the powder risked exploding the barrel, with the condition known as a "short start".)[16]
The loading of muskets was therefore easy with the old smooth-boreBrown Bess and similar military muskets. The original muzzle-loadingrifle, however, was loaded with a piece of leather or cloth wrapped around the ball, to allow the ball to engage the grooves in the barrel. Loading was a bit more difficult, particularly when the bore of the barrel was fouled from previous firings. For this reason, and because rifles were not often fitted forbayonets, early rifles were rarely used for military purposes, compared to muskets.
There was a distinct change in the shape and function of the bullet during the first half of the 19th century, although experiments with various types of elongated projectiles had been made in Britain, America and France from the first half of the 18th century onwards.[17][18] In 1816, Capt. George Reichenbach of the Bavarian army invented a rifled-wall musket using cylindro-conical ammunition.[19] In 1826,Henri-Gustave Delvigne, a Frenchinfantry officer, invented a breech with abrupt shoulders on which a spherical bullet was rammed down until it caught therifling grooves. Delvigne's method, however, deformed the bullet and was inaccurate. In 1855, a detachment of1st U.S. Dragoons, while on patrol, traded lead for gold bullets withPima Indians along the California–Arizona border.[20][21]
Square bullets have origins that almost pre-date civilization and were used in slings. They were typically made out of copper or lead. The most notable use of square bullet designs was byJames Puckle and Kyle Tunis who patented them, where they were briefly used in one version of thePuckle gun. The early use of these in theblack-powder era was soon discontinued because of the irregular and unpredictable flight patterns.
Delvigne further developed cylindro-spherical (left) and cylindro-conical bullets (middle), which received the bullet grooves developed byTamisier for stability
Delvigne continued to develop bullet design and by 1830 had started to develop cylindro-conical bullets. His bullet designs were improved byFrancois Tamisier with the addition of "ball grooves" which are known as "cannelures", which moved the resistance of air behind the center of gravity of the bullet.[22] Tamisier also developed progressive rifling: the rifle grooves were deeper toward the breech, becoming shallower as they progressed toward the muzzle. This causes the bullet to be progressively molded into the grooves which increases range and accuracy.[23][24]
Before Tamisier's invention, the orientation of a cylindro-conical bullet tended to remain along its inertial axis, progressively setting it against its trajectory and increasingly meeting air resistance, which rendered the bullet's movement erratic.
Among the first pointed or "conical" bullets were those designed by Captain John Norton of theBritish Army in 1832. Norton's bullet had a hollow base made oflotus pith that on firing expanded under pressure to engage with a barrel's rifling.[25] The British Board of Ordnance rejected it because spherical bullets had been in use for the previous 300 years.[26] Renowned English gunsmithWilliam Greener invented the Greener bullet in 1836. Greener fitted thehollow base of an oval bullet with a wooden plug that more reliably forced the base of the bullet to expand and catch the rifling. Tests proved that Greener's bullet was effective, but the military rejected it because, being two parts, they judged it as too complicated to produce.[27]
Minié ball ammunition
Thecarabine à tige, developed byLouis-Étienne de Thouvenin in 1844, was an improvement of Delvigne's design. The rifle barrel has a forcing plug in the breech of the barrel to mold the bullet into the rifling with the use of a specialramrod. While successful in increasing accuracy, it was difficult to clean.
1855 Minié ball design from the U.S. Arsenal, Harper's Ferry, West Virginia
The soft leadMinié ball was first introduced in 1847 byClaude-Étienne Minié, a captain in the French Army. It was another improvement of the work done by Delvigne. The bullet was conical in shape with a hollow cavity in the rear, which was fitted with a small iron cap instead of a wooden plug. When fired, the iron cap forced itself into the hollow cavity at the rear of the bullet, thus expanding the sides of the bullet to grip and engage the rifling. In 1851, the British adopted the Minié ball for their702-inch Pattern 1851 Minié rifle. In 1855, James Burton, a machinist at the U.S. Armory atHarper's Ferry, West Virginia, improved the Minié ball further by eliminating the metal cup in the bottom of the bullet.[28][29] The Minié ball first saw widespread use in theCrimean War (1853–1856). Roughly 90% of the battlefield casualties in theAmerican Civil War (1861–1865) were caused by Minié balls fired from rifled muskets.[30] A similar bullet called theNessler ball was also developed forsmoothbore muskets.[31]
Between 1854 and 1857, SirJoseph Whitworth conducted a long series of rifle experiments and proved, among other points, the advantages of a smallerbore and, in particular, of an elongated bullet. The Whitworth bullet was made to fit the grooves of the rifle mechanically. The Whitworth rifle was never adopted by the government, although it was used extensively for match purposes and target practice between 1857 and 1866. In 1861, W. B. Chace approached PresidentAbraham Lincoln with an improved ball design for muskets. In firing over thePotomac River, where the Chace ball and the round ball were alternated, Lincoln observed that the Chace design carried a third or more farther fired at the same elevation. Although Lincoln recommended testing, it never took place.[32]
Around 1862,W. E. Metford carried out an exhaustive series of experiments on bullets and rifling, and he invented the important system of light rifling with increasing spiral and a hardened bullet. The combined result was that, in December 1888, theLee–Metford small-bore (.303", 7.70 mm) rifle, Mark I, was adopted for the British army. The Lee–Metford was the predecessor of theLee–Enfield.[33]
The next important change in the history of the rifle bullet occurred in 1882, when Lieutenant ColonelEduard Rubin, director of the Swiss Army Laboratory at Thun, invented thecopper-jacketed bullet — an elongated bullet with a lead core in a copper jacket. It was also small bore (7.5 and 8 mm) and it is the precursor of the 8 mmLebel bullet adopted for thesmokeless powder ammunition of theLebel Model 1886 rifle. The surface of lead bullets fired at high velocity may melt from the hot gases behind and friction within the bore. Because copper has a highermelting point, and greaterspecific heat capacity, and higherhardness, copper-jacketed bullets allow greater muzzle velocities.
.303 inch (7.7 mm) centrefire,FMJ rimmed ammunition
European advances in aerodynamics led to the pointedspitzer bullet. By the beginning of the 20th century, most world armies had begun the transition to spitzer bullets. These bullets flew for greater distances more accurately and transferred morekinetic energy. Spitzer bullets combined withmachine guns greatly increased lethality on the battlefield.
Spitzer bullets were streamlined at the base with theboat tail. In the trajectory of a bullet, as air passes over a bullet at high speed, a vacuum is created at the end of the bullet, slowing the projectile. The streamlined boat tail design reduces thisform drag by allowing the air to flow along the surface of the tapering end. The resulting aerodynamic advantage is currently seen as the optimum shape for rifle technology. The first combination spitzer and boat-tail bullet, namedballe D by its inventor Captain Georges Desaleux, was introduced as standard military ammunition in 1901, for the FrenchLebel Model 1886 rifle.
Aballistic tip bullet is ahollow-point rifle bullet that has a plastic tip on the end of the bullet. This improvesexternal ballistics by streamlining the bullet, allowing it to cut through the air more easily, and improvesterminal ballistics by allowing the bullet to act as a jacketed hollow point. As a side effect, it also feeds better in weapons that have trouble feeding rounds that are not full metal jacket rounds.
Bullet designs have to solve two primary problems. In the barrel, they must first form a seal with the gun's bore. If a strong seal is not achieved, gas from the propellant charge leaks past the bullet, thus reducing efficiency and possibly accuracy. The bullet must also engage the rifling without damaging or excessively fouling the gun's bore and without distorting the bullet, which will also reduce accuracy. Bullets must have a surface that forms this seal without excessive friction. These interactions between bullet and bore are termedinternal ballistics. Bullets must be produced to a high standard, as surface imperfections can affect firing accuracy.
The physics affecting the bullet once it leaves the barrel is termedexternal ballistics. The primary factors affecting the aerodynamics of a bullet in flight are the bullet's shape and the rotation imparted by the rifling of the gun barrel.[34] Rotational forces stabilize the bullet gyroscopically as well as aerodynamically. Any asymmetry in the bullet is largely canceled as it spins. However, a spin rate greater than the optimum value adds more trouble than good, by magnifying the smaller asymmetries or sometimes resulting in the bullet breaking apart in flight. With smooth-bore firearms, a spherical shape is optimal because no matter how the bullet is oriented, its aerodynamics are similar. These unstable bullets tumble erratically and provide only moderate accuracy; however, the aerodynamic shape changed little for centuries. Generally, bullet shapes are a compromise between aerodynamics, interior ballistic necessities, andterminal ballistics requirements.
Terminal ballistics andstopping power are aspects of bullet design that affect what happens when a bullet impacts with an object. The outcome of the impact is determined by the composition and density of the target material, theangle of incidence, and the velocity and physical characteristics of the bullet. Bullets are generally designed to penetrate, deform, or break apart. For a given material and bullet, the strike velocity is the primary factor that determines which outcome is achieved.
Bullet shapes are many and varied. With a mold, bullets can be made at home for reloading ammunition, where local laws allow. Hand-casting, however, is only time- and cost-effective for solid lead bullets. Cast and jacketed bullets are also commercially available from numerous manufacturers forhandloading and are most often more convenient than casting bullets from bulk or scrap lead.
In recent years, manufacturers have introduced bullet designs that rely on computer numerical control (CNC) machining to achieve precise, repeatable geometries not possible with traditional swaging or casting. These designs often feature patented profiles with radial flutes, pressure cavities, or meplat modifications intended to manipulate fluid displacement, induce controlled expansion, or promote bullet tumbling upon impact.
One notable example includes the designs patented by Lehigh Defense, which incorporate machined flutes that channel hydraulic force to create large wound cavities and ensure consistent terminal performance. These bullets are often monolithic in composition and used in hunting and self-defense contexts where expansion and barrier penetration are critical.[35][36][37]
Expanding bullet loaded in a6.5×55mm before and after expanding. The long base and small expanded diameter show that this is a bullet designed for deep penetration onlarge game. The bullet in the photo traveled more than halfway through a moose before coming to rest, performing as designed.
Bullets for black powder, or muzzle-loading firearms, were classically molded from purelead. This worked well for low-speed bullets, fired at velocities of less than 450 m/s (1,475 ft/s). For slightly higher-speed bullets fired in modern firearms, a harderalloy of lead and tin or typesetter's lead (used to moldlinotype) works very well. For even higher-speed bullet use, jacketed lead bullets are used. The common element in all of these, lead, is widely used because it is very dense, thereby providing a high amount of mass—and thus, kinetic energy—for a given volume. Lead is also cheap, easy to obtain, easy to work, and melts at a low temperature, which results in comparatively easy fabrication of bullets.
Lead: simplecast, extruded,swaged, or otherwise fabricated leadslugs are the simplest form of bullets. At speeds of greater than 300m/s (1,000 ft/s) (common in mosthandguns), lead is deposited in rifled bores at an ever-increasing rate. Alloying the lead with a small percentage oftin and/orantimony serves to reduce this effect but grows less effective as velocities are increased. A cup made of harder metal, such as copper, placed at the base of the bullet and called agas check, is often used to decrease lead deposits by protecting the rear of the bullet against melting when fired at higher pressures, but this does not solve the problem at higher velocities. A modern solution is topowder coat the lead projectile, encasing it in a protective skin, allowing higher velocities to be achieved without lead deposits.
Jacketed lead: bullets intended for even higher-velocity applications generally have a lead core that is jacketed or plated withgilding metal,cupronickel,copper alloys, orsteel; a thin layer of harder metal protects the softer lead core when the bullet is passing through the barrel and during flight, which allows delivering the bullet intact to the target. There, the heavy lead core delivers its kinetic energy to the target. Full metal jacket or "ball" bullets (cartridges with ball bullets, which despite the name are not spherical, are called ball ammunition) are completely encased in the harder metal jacket, except for the base. Some bullet jackets do not extend to the front of the bullet, to aid expansion and increase lethality; these are called soft point (if the exposed lead tip is solid) or hollow point bullets (if a cavity or hole is present). Steel bullets are often plated with copper or other metals for corrosion resistance during long periods of storage. Synthetic jacket materials such asnylon andTeflon have been used, with limited success, especially in rifles; however, hollow point bullets with plastic aerodynamic tips have been very successful at both improving accuracy and enhancing expansion. Newer plastic coatings for handgun bullets, such asTeflon-coated bullets, are making their way into the market.
Hard cast solid bullet (left), with gas check (center) and lubrication (right)A moderncenterfirecartridge consisting of the following:1.bullet, as theprojectile;2.metalliccase, which holds all parts together;3.propellant, for examplegunpowder orcordite;4.rim, which provides the extractor on the firearm a place to grip the case to remove it from the chamber once fired;5.primer, which ignites the propellant.
Solid ormonolithic solid: mono-metal bullets intended for deep penetration in big game animals and slender shaped very-low-drag projectiles for long range shooting are produced out of metals like oxygen-free copper and alloys likecupronickel,tellurium copper andbrass (e.g., highly machinable UNS C36000 free-cutting brass). Often these projectiles are turned on precisionCNC lathes. In the case of solids, and the ruggedness of the game animals on which they are used, e.g., the African buffalo or elephant, expansion is almost entirely relinquished for the necessary penetration. In shotgunning, "slug" loads are often solid large single lead projectiles, sometimes with a hollow point, used for deer or wild pig hunting in jurisdictions that do not allow hunting with rifles (because a missed slug shot will travel considerably less far than a rifle bullet).
Fluted: in appearance, these are solid bullets with scalloped sides (missing material). The theory is that the flutes produce hydraulic jetting when passing through tissue, creating a wound channel larger than that made by conventionalexpanding ammunition such as hollow point bullets.
Hard cast: a hard lead alloy intended to reduce fouling of rifling grooves (especially of thepolygonal rifling used in some popular pistols). Benefits include simpler manufacture than jacketed bullets and good performance against hard targets; limitations are an inability tomushroom and subsequent over-penetration of soft targets.
Blank: wax, paper, plastic, and other materials are used to simulate live gunfire and are intended only to hold the powder in a blank cartridge and to produce noise, flame and smoke. The "bullet" may be captured in a purpose-designed device or it may be allowed to expend what little energy it has in the air. Some blank cartridges are crimped or closed at the end and do not contain any bullet; some are fully loaded cartridges (without bullets) designed to propel rifle grenades. The force of the expanding gas from blank cartridges can be lethal at short range; fatal accidents have occurred with blank cartridges (e.g., the death of actorJon-Erik Hexum).
Practice: made from lightweight materials like rubber,wax, wood, plastic, or lightweight metal, practice bullets are intended for short-range target work only. Because of their weight and low velocity, they have limited range.
Polymer: these are metal-polymer composites, generally lighter and having higher velocities than pure metal bullets of the same dimensions. They permit unusual designs that are difficult with conventional casting or lathing.
Less lethal, orless than lethal:Rubber bullets,plastic bullets, andbeanbags are designed to benon-lethal, e.g., for use inriot control. They are generally low velocity and are fired from shotguns, grenade launchers, paint ball guns, or specially designed firearms and air gun devices.
Incendiary: these bullets are made with explosive or flammable mixtures in the tips that are designed to ignite on contact with a target. The intent is to ignite fuel or munitions in the target area, thereby adding to the destructive power of the bullet.
Exploding: similar to the incendiary bullet, this type of projectile is designed to explode upon hitting a hard surface, preferably the bone of the intended target. Not to be mistaken for cannon shells or grenades with fuse devices, these bullets have only cavities filled with a small amount of high explosive depending on the velocity and deformation upon impact to detonate. Exploding bullets have been used in variousheavy machine guns and inanti-materiel rifles.
Tracer: these have hollow backs, filled with aflare material. Usually this is a mixture ofmagnesium, aperchlorate, andstrontium salts to yield a bright red color, although other materials providing other colors have also sometimes been used. Tracer material burns out after a certain amount of time. This allows the shooter to visually trace the flight path of the projectile and thus make necessary ballistic corrections, without having to confirm projectile impacts and without even using thesights of the weapon. This type of round is also used by all branches of theUnited States military in combat environments as a signaling device to friendly forces. Normally it is loaded at a four to one ratio with ball ammunition.
Armor-piercing: jacketed designs where the core material is a very hard, high-density metal such astungsten,tungsten carbide,depleted uranium, orsteel. A pointed tip is often used, but a flat tip on the penetrator portion is generally more effective.[38]
Nontoxic shot: steel,bismuth, tungsten, and other alloys prevent release of toxic lead into the environment. Regulations in several countries mandate the use of nontoxic projectiles especially whenwaterfowl hunting. It has been found that birds swallow small lead shot for theirgizzards to grind food (as they would swallow pebbles of similar size), and the effects oflead poisoning by grinding of lead pellets against food means lead poisoning effects are magnified. Such concerns apply primarily to shotguns firing pellets (shot) and not bullets, but there is evidence suggesting that consumption of spent rifle and pistol ammunition is also hazardous to wildlife.[39] Reduction of hazardous substances legislation has also been applied to bullets on occasion to reduce the impact of lead on the environment atshooting ranges.
Blended-metal: bullets made using cores from powdered metals other than lead with binder or sometimessintered.
Frangible: designed to disintegrate into tiny particles upon impact to minimize their penetration for reasons of range safety, to limit environmental impact, or to limit the shoot-through danger behind the intended target. An example is theGlaser Safety Slug, usually a pistol caliber bullet made from an amalgam of lead shot and a hard (and thus frangible) plastic binder designed to penetrate a human target and release its component shot pellets without exiting the target.
Multiple projectile: bullets that are made of separate slugs that fit together inside the cartridge and act as a single projectile inside the barrel as they are fired. The projectiles part in flight but are held in formation by tethers that keep the individual parts of the "bullet" from flying too far away from each other. The intention of such ammo is to increase hit chance by giving a shot-like spread to rifled slug firing guns, while maintaining a consistency in shot groupings. Multiple impact bullets may be less stable in flight than conventional solid bullets because of the addeddrag from the tether line holding the pieces in formation, and each projectile affects the flight of all the others. This may limit the benefit provided by the spread of each bullet at longer ranges.
Expanding bullets are designed to increase in diameter upon impact with a target, maximizing the transfer of energy and creating a larger wound channel.[40] These bullets are often made with alead core and acopper jacket, though variations like MRX bullets havetungsten in its core.[41] Thepolymer tip in expanding bullets is designed to enhanceaerodynamics for shooting at flat long-range trajectories.[42]
^"How to load a musket".tamu.edu. The Second Flying Company of Alamo de Parras. Archived fromthe original on 3 July 2017. Retrieved29 January 2017.
^The Principles and Practice of Modern Artillery; Including Artillery Material, Gunnery, and Organization and Use of Artillery in Warfare ... With ... Illustrations by Charles Henry OWEN (Major-General.) p.200[1]
^Rifled Field Pieces: A Short Compilation of what is Known of the New Field Artillery of Europe : with Some Account of Our Own by Franck Taylor p.29[2]
^Bennett, James A.; Editors Brooks, Clinton E., Reeve, Frank D. (1948) p, 72.Forts and Forays, James A. Bennett: A Dragoon In New Mexico1850-1856. The University of New Mexico Press, Albuquerque.
^Bieber, Ralph P., Editor (1938). P. 370."Diaries of Francois Xavier Aubry 1853–1854." "Exploring Southwestern Trails 1846–1854." The Arthur H. Clarke Company.
^Passas, Nikos; Goodwin, Neva (2005).It's Legal but It Ain't Right: Harmful Social Consequences of Legal Industries (Evolving Values For A Capitalist World). University of Michigan Press.doi:10.3998/mpub.11472.
