Bullet

From Wikipedia, the free encyclopedia

This is an old revision of this page, as edited by PierreAbbat (talk | contribs) at 16:16, 4 August 2002 (Neither tin nor copper *is*. "Or" and "nor" are alternative conjunctions, and if both sides are singular, so is the phrase. Both are, but neither is.). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

Jump to navigation Jump to search

A bullet is the metal projectile shot by a hand-held gun.

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 jacketted with copper to make them harder.

Steel jacketted 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 is toxic to mammals.

Design

Bullet designs have to solve several problems:

  1. 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. Anotehr type is a basic labyrnthine seal: one or two bands of raised material go around the bullet.
  2. 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 "boattail", a barrowing and rounding-off toward the end to reduce vacuums 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 haved rounded fronts.
  3. The bullet must accomplish its mission: usually, penetrate the target. Bullets either cut tissue, or damage it by causing a hydrostatic shockwave. Therefore, subsonic bullets have to cut the biggest possible hole. 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 vutsd through the flesh. The dum=dum is just such a bullet, usually a hard metal outer shell, and a soft led interior and hack. 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. 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.
  4. The bullet must engage the rifling without damaging the gun's bore. Usually there's a raised band of material around its middle.

History

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

In the 1840s, expermimenter Joseph Mini 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.

Mini's shape, the Mini ball was used in the Civil War where it proved to have a range three times as long as the conventional musketball. The resulting casualties were a tremendous surprise to combatants.

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 destructivee.

See also gun, cartridge, percussion cap and weapon.