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Bullet

A bullet is the metal projectile shot by a hand-held gun. They are part of a cartridge. As opposed to a shell, a bullet does not contain explosives.

Table of contents

Material

Bullets are classically molded from a mixture of lead and tin. Typesetter's lead (used to mold Linotype), works very well.

Some bullets are jacketed with copper or steel to make them harder.

Steel jacketed bullets are actually copper-dipped so that the steel will not damage the gun's rifling.

Bismuth bullet alloys are available, and prevent release of toxic lead into the environment. Neither tin nor copper are toxic to mammals.

Rubber bullets are designed to be non-lethal, for example for use in riot control.

Design

Bullet designs have to solve several problems:

The bullet must seal somewhat to the gun's bore. If it doesn't, the gas from the gunpowder will blow right by.

There are two types of seals in common use. One is a slight indentation in the back of the bullet. Gas pressure forces the metal lip against the bore.

Another type is a basic labyrinthine seal: one or two bands of raised material go around the bullet.

The bullet must not tumble in flight. This causes a dramatic loss of speed and energy. The tricks here vary depending on the design speed.

Supersonic bullets are pointed, smoothly sloping back to the rear. The longest-range supersonic bullets have a boat-tail, a narrowing and rounding-off toward the end to reduce vacuum on the back of the bullet.

Transonic bullets, such as deer slugs and air-gun pellets are double cones, going wide to narrow to wide. Basically, the narrow waist prevents auxiliary shockwaves from forming, and tumbling the bullet.

Subsonic bullets generally have rounded fronts.

The bullet must accomplish its mission: usually, penetrate the target. Bullets either cut tissue, or damage it by causing a hydrostatic shockwave.

Since subsonic bullets lack a shock wave, they have to cut the biggest possible hole in order to maximise their damage.

One way is to drill the front of the bullet, and possibly scribe the copper shell. When the bullet hits it will unfold into a sharp-edged flower that cuts through flesh.

The dum-dum is also an expanding bullet. It has a hard metal outer shell, and a soft lead interior and hack. When it hits, the lead cracks the metal shell, and flows into a wide, mushroom shape.

The Russian ammunition for the AK-47 had a bullet with a hard steel shell, a soft lead interior. a steel penetrator, and a bubble in the nose. Before shooting, the bullet was dynamically stable. After it hits, the interior lead deforms, causing the bullet to unbalance and tumble. The tumble was designed to cause the bullet to make exactly two flips in 40 CM, roughly the thickness of a human body. This maximizes hydrodynamic shock, but does not violate the Geneva Accords on Humane Weaponry.

Subsonic bullets with rounded fronts often glance off their target if it is at an angle. To prevent this, many people use wad cutters or semi wad cutters with flattened noses. The flat nose interferes with feeding a self-loading gun. Full wadcutters are usually only shot from revolvers or single-shot guns.

A variation is to have a ring of small teeth, covered by a soft plastic nose so that the bullet will feed correctly in self-loading guns. The teeth engage a sloping surface.

At close to moderate ranges, an explosive bullet is only slightly more effective than an expanding bullet. In most cases, they are not worth the extra expense and danger to the user. PETN is the standard explosive used in bullets.

Tracer bullets have a hollow back, filled with a flare material. Usually this is a mixture of magnesium, perchlorate, and chromium, to yield a bright red color.

Poisoned bullets are neglected by the industry. Theoretically, a .177 calibre bullet (the smallest in general use) should be able to carry enough curare to kill quite a large animal. This would also permit small, lethal guns. One obstacle may be the lack of an inexpensive stable poison that is edible. However, it does not explain why poisons remain unused.

The bullet must engage the rifling without damaging the gun's bore. Usually there's a raised band of material around its middle.

Manufacture

Small-scale manufacture is accomplished with individual molds, and hand-file to remove the mold artifacts. Larger scales use multiple molds, and abrasive tumbling to remove separation lines and other mold artifacts.

Treaties

The Geneva Accords on Humane Weaponry[?] prohibit certain kinds of ammunition for use by armies. These include exploding, poisoned and expanding bullets.

History

Bullets started out as lead balls, made by dropping molten lead through sieves in "shot towers." The lead would solidify as it fell and cooled.

In the 1840s, inventor Joseph Minie[?] noted that rifled bores spin a bullet, and the gyroscopic stabilization allowed a cylindrical bullet to remain end-to-the-target, and be more aerodynamic.

Minie's shape, the Mini ball was used in the American Civil War where it proved to have a range three times as long as the conventional musket ball. The resulting casualties were a tremendous surprise to combatants. In some cases, the minibal shot farther than cannons.

The basic bullet has had minor refinements, but has since remained almost unchanged.

In the late 1950s, engineers noted that a reverse ogive on the rear, a boat-tail increased range on supersonic bullets.

At one point in the 1960s, it looked as though flechettes might replace bullets, but bullets proved more economical, and no less destructive.

The original musket bullet was a spherical leaden ball two sizes smaller than the bore, wrapped in a loosely fitting paper patch which formed the cartridge. The loading was, therefore, easy with the old smooth-bore Brown Bess and similar military muskets. The original muzzle-loading rifle, on the other hand, with a closely fitting ball to take the grooves, was loaded with difficulty, particularly when foul, and for this reason was not generally used for military purposes.

In 1826 Delirque, a French infantry officer, invented a breech with abrupt shoulders on which the spherical bullet was rammed down until it expanded and filled the grooves. The objection in this case was that the deformed bullet had an erratic flight. The Brunswick rifle, introduced into the British army in the reign of William IV of England[?], fired a spherical bullet weighing 557 grains with a belt to fit the grooves. The rifle was not easily loaded, and soon fouled. In 1835 W. Greener produced a new expansive bullet, an oval ball, a diameter and a half in length, with a flat end, perforated, in which a cast metallic taper plug was inserted. The explosion of the charge drove the plug home, expanded the bullet, filled the grooves and prevented windage. A trial of the Greener bullet in August 1835, at Tynemouth, by a party of the 60th (now King's Royal) Rifles, proved successful. The range and accuracy of the rifle were retained, while the loading proved as easy as with a smooth-bore musket. The invention was, however, rejected by the military authorities on the ground that the bullet was a compound one. In 1852 the government awarded Minie, a Frenchman, L. 20,000 for a bullet of the same principle, adopted into the British service. Subsequently, in 1857, Greener was also awarded L. 1000 for "the first public suggestion of the principle of expansion, commonly called the Minie principle, in 1836." The Minie bullet contained an iron cup in a cavity in the base of the bullet. The form of the bullet was subsequently changed from conoidal to cylindro-conoidal, with a hemispherical iron cup. This bullet was used in the Enfield rifle introduced into the British army in 1855. It weighed 530 grains, and was made up into cartridges and lubricated as for the Minie rifle. A boxwood plug to the bullet was also used. The bullet used in the breech-loading Martini-Henry rifle, adopted by the British government in 1871 in succession to the Snider-Enfield rifle, weighed 480 grains, and was fired from an Eley-Boxer cartridge-case with a wad of wax lubrication at the base of the bullet.

Between 1854 and 1857 Sir Joseph Whitworth conducted a long series of rifle experiments, and proved, among other points, the advantages of a smaller bore 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, when it was gradually superseded by Metford's System mentioned below.

The next important change in the history of the rifle bullet occurred in 1883, when Major Rubin, director of the Swiss Laboratory at Thun, invented the small-calibre rifle, one of whose essential features was the employment of an elongated compound bullet, with a leaden core in a copper envelope. About 1862 and later, W. E. Metford had carried out an exhaustive series of experiments on bullets and rifling, and had invented the important system of light rifling with increasing spiral, and a hardened bullet. The combined result of the above inventions was that in December 1888 the Lee-Metford small-bore .303 rifle, Mark I, was finally adopted for the British army. The latest development of this rifle is now known as the .303 Lee-Enfleld, which fires a long, thin, nickel-covered, leaden-cored bullet 1.25 inches long, weighing only 215 grains, while the Martini-Henry bullet, 1.27 inches in length and .45 inches in diameter, weighed 480 grains.

The adoption of the smaller elongated bullet, necessitated by the smaller calibre of the rifle, entailed some definite disadvantages. The lighter bullet is more affected by wind. Its greater relative length to diameter necessitates a sharper pitch of rifling in order properly to revolve the bullet (one turn in 10 inches for the .303 rifle as compared with one turn in 22 inches for the Martini-Henry). This, in its turn, necessitates a hard nickel envelope for the leaden bullet in order to prevent its "stripping," or being forced through the barrel without rotation. The general result is that, while the enveloped bullet has a much higher penetrative power than one of lead only, it does not usually inflict so severe a wound, nor has it such a stunning effect as the old lead bullet. It cuts a small clean hole, but does not deform. This fact is of some military importance, as, for example, in warfare with savages, in which the chief danger is usually a rush of large numbers at close quarters. The advantages, however, of the smaller calibre and the lighter bullet and ammunition are considered to outweigh the disadvantages, and they have been universally adopted for all military rifles.

Bullets for target and sporting-rifles have, in the main, followed, or occasionally preceded, the line of progress of military rifle bullets. In 1861 Henry introduced a modification of the grooving of the cylindrical Whitworth bullet, and in 1864 and 1865 the Rigby mechanically fitting bullet was used with success at the National Rifle Association meeting, and in the second stage of the Queen's prize. The bullets of sporting rifles, and particularly those of Express rifles, are often lighter than military bullets, and made with hollow points to ensure the expansion of the projectile on or after impact. The size and shape of the hollow in the point vary according to the purpose required and the nature of the game hunted. If greater penetration is needed, the leaden bullet is hardened with mercury or tin, or the military nickel-coated bullet is used with the small-bore, smokeless-powder rifles. Explosive bullets filled with detonating powder were at one time used in Express and large-bore rifles for large game. The use of these bullets is now practically abandoned owing to their uncertainty of action and the danger involved in handling them. Their use in warfare is prohibited by international law.

The nickel-covered bullet, when used in a modern small-bore rifle for sporting purposes, is made into an expanding bullet, either by leaving the leaden core uncovered at the nose of the bullet, with or without a hollow point, or by cutting transverse or longitudinal nicks of varying depth in the point or circumference of the bullet.

A cone-shaped sharp-pointed bullet, named the Spitzer bullet, has been tried in the United States under the auspices of the Ordnance Department, in a Springfield rifle, which is practically identical with the British service .303 Lee-Enfield. This bullet is lighter than the Lee-Enfield bullet (150 grains as against 215 grains), and when fired with a heavier charge of powder (51 grains as against 31 grains) gives, it is claimed, better results in muzzle-velocity, trajectory, deflexion from wind and wear and tear of rifling, than the present universally used cylinder-shaped bullet. In 1906 details of its prototype, the German "S" bullet (Spitzgeschoss), and of the French "D" bullet, were published.

See also: gun, cartridge, percussion cap, weapon, ammunition, terminal ballistics


A bullet is a typographic symbol.



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