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.
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2 Design 3 Manufacture 4 Treaties 5 History |
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.
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.
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.
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.
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 Minie 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, List of cartridges (weaponry), pistol and rifle
A bullet is a typographic symbol.Material
Design
Manufacture
Treaties
History
