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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
1 Material
2 Design
3 Manufacture
4 Treaties
5 History

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. This 'coke bottle' shape is also apparent in high speed aircraft.

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, creating a hollow point 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 and the Hague Convention prohibit certain kinds of ammunition for use by armies. These include exploding, poisoned and expanding bullets.

History

The first bullets

Almost undoubtedly the first "bullets" were much like crossbow quarrels, fired from metal and wooden guns immediately after the introduction of gunpowder in Europe. Large guns and cannon initially fired stone balls until the mid-15th century when metal balls began to be cast.

The development of the hand culverin and matchlock arquebus brought about the use of cast lead balls as projectiles. "Bullet" is derived from the French word "boulette" which roughly means "little ball." 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 rifling grooves, was loaded with difficulty, particularly when foul, and for this reason was not generally used for military purposes.

The bullet takes shape

As firearms became more technologically advanced in between 1500-1800, the bullets changed little. They remained simple round lead balls, differing only in their size (caliber). Even with the advent of rifling the bullet itself didn't change, but was wrapped in a leather patch to grip the rifling grooves.

The first half of the 19th century saw a distinct change in the shape and function of the bullet. In 1826 Delirque, a French infantry officer, invented a breech with abrupt shoulders on which a spherical bullet was rammed down until it caught the rifling grooves. Delirque's method, however, deformed the bullet and was inaccurate.

Among the first "bullet-shaped" bullets was designed by Captain John Norton of the British Army in 1823. Norton's bullet had a hollow base which expanded under pressure to catch the rifling grooves once fired but the British Board of Ordnance rejected it only because spherical bullets has been in use for the last 300 years.

Renowned English gunsmit William Greener invented the Greener bullet in 1836. It was very similar to Norton's bullet except that the hollow base of the bullet was fitted with a wooden plug which more reliably forced the base of the bullet to expand and catch the rifling. Tests proved that Greener's bullet was extremely effective but it was rejected because, being two parts, was judged too complicated to produce.

The soft lead bullet that came to be known as the minie ball (or minnie ball) was first introduced in 1847 by Claude …tienne Miniť (1814? - 1879), a captain in the French Army. It was nearly identical to the Greener bullet: as designed by Miniť the bullet was conical in shape with with a hollow cavity in the rear end, which was fitted with a little iron cap instead of a wooden plug. When fired, the cap would force itself into the hollow cavity, forcing the sides of the bullet to expand and engage the rifling. In 1855 the British adopted the minie ball for their Enfield rifled muskets.

It was in the American Civil War, however, that the minie ball saw the most use. Roughly 90% of the battlefield casualties in the war were caused by minie balls fired from rifled muskets.

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.

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 Lee-Metford was the predecessor of the Lee-Enfield.

The modern bullet

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.

The modern bullet has had minor refinements, but the basic bullet and self-contained cartridge has since remained almost unchanged for over 130 years.

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.

See also: gun, cartridge, percussion cap, weapon, ammunition, terminal ballistics, List of cartridges (weaponry), pistol and rifle


A bullet is a typographic symbol.