Section 7-Bullets

Caliber

(1) A term used to designate the specific cartridge for which a firearm is chambered. (2) In firearms, caliber is the approximate diameter of the circle formed by the tops of the lands of a rifled barrel, typically expressed in hundredths of an inch (38 caliber) or millimeters (9mm caliber). (3) In ammunition, caliber is a numerical term, without the decimal point, included in a cartridge name to indicate the nominal bullet diameter.

Following Edge

(Also known as the trailing edge) a bullet fired from a gun with a right twist is the left edge of the land impression, or the right edge of the groove impression. The trailing edge of a bullet fired from a gun with left twist is the right edge of the land impression or the left edge of the groove impression.

Leade (lay-aid)

(Chamber Throat) the section of the bore of a rifled gun barrel located immediately ahead of the chamber in which the rifling is conically removed to provide clearance for the seated bullet. Also known as ball seat or leade.

Grain

1) a unit of weight commonly used in American and English ammunition. 2) an individual kernel of black powder.

Base

1) the rear portion of the bullet that is opposite of the nose. Also known as the heel. 2) the portion of the cartridge case which contains the primer or filler material which constitutes the lowest or base wad in a shotshell.

Balloting

A bullet ballots when it moves through the bore of a firearm with a bumping, buffeting action. Yawning motion while traveling down the bore, resulting in incomplete, intermittent rifling impressions and often extends to the ogive of the bullet.

Soft-point bullet

A design providing for exposure of a portion of the core at the nose of a jacketed projectile.

Step Base

A jacketed bullet having a small, flat recess or "step" in its base.

Gas Check Bullet

A lead alloy bullet with a copper or gilding metal cup pressed over the base

Gas check bullet

A lead alloy projectile with a copper or gilding metal cup pressed over the base. This metal cup is used to protect the base of a bullet from deformation due to the hot gases produced during firing.

Spitzer Bullet

A projectile design having a sharp pointed nose, a long ogive, and sometimes a boattail base.

Frangible

A projectile designed to disintegrate upon impact with a hard surface in order to minimize ricochet. Sometimes referred to as a disintegrating bullet or gallery bullet.

Spire Point Bullet

A projectile with a conical nose profile.

Boat-tail

A specific design of bullet having a tapered or a truncated conical base.

Meplat

A term describing the flat, measurable portion of a bullet, specifically the tip's diameter.

Projectile

An object propelled by external force and continuing in motion by its own inertia.

Cannelures

Grooves around a bullet or cartridge case that provide a means of crimping, lubricating and identification of the cartridge case to the bullet.

Gliding Metal

Metal alloys of 90 or 95 percent copper and the remainder zinc. Also termed COMMERCIAL BRONZE. Neither name is recommended by Cooper Development Association, Inc., but instead Alloy No. 220 and Alloy No. 210 respectively are recommended. It is used extensively for the manufacture of bullet jackets

Misalignment Marks

Reproducible striations on a bullet which occur during firing and before engagement with the rifling. These are caused by the misalignment of the bullet with the axis of the bore. Also called AXIAL ENGRAVING, FORCING CONE MARKS and OUT-OF-TIME MARKS.

Bullet Slippage

Slippage marks are typically produced by revolvers and have the appearance of widening of the land impressions at their beginning point. Also known as skid marks or jump marks

Bullet Jump Marks

Striations or contours on a fired bullet that run parallel or approximately parallel to the axis of the bullet due to the rifling, prior to engagement with and rotation of the bullet.

Axial Engraving

Striations or contours on a fired bullet that run parallel or approximately parallel to the axis of the bullet. There are several possible types of axial engravings, including, but not limited to marks left by or due to: 1) the mouth of the cartridge case; 2) the chamber throat; 3) irregularities or burrs along the forward edge of a chamber in a revolver cylinder; 4) inconsistent rotation of a bullet as it moves down the bore; 5) misalignment of a revolver chamber with the axis of the bore (also known as forcing cone marks, misalignment marks, or out-of-time marks); and 6) the rifling, prior to engagement with and rotation of the bullet (also known as slippage marks, skid marks, or jump marks).

Bearing surface

That portion of a bullet's outer surface that comes into direct contact with the interior surface of the barrel.

Bullet Ogive

The curved forward part of a bullet.

Shaving

The cutting of metal from a bullet due to a cylinder misalignment in a revolver.

Bullet Jump

The distance that a bullet must travel from its position at rest in the cartridge case to its initial engagement with the barrel's rifling. Also referred to as FREE TRAVEL.

Blow-by

The escaping of gases past the bullet, while the bullet is in the barrel. May also be used in reference to leakage of gas around a bullet fired through the baffles in a suppressor.

Bullet Core

The inner portion of a jacketed bullet often made of lead.

Bullet Creep

The movement of a bullet out of the cartridge case due to the recoil of the firearm and the inertia of the bullet.

Mold line

The residual line on a bullet resulting from the flow of metal into the juncture where the two mold halves come together.

Obturation

The sealing of a bore and chamber by pressure. During the firing process, pressure swells the cartridge case against the chamber walls which minimizes the rearward flow of gases between the case and the camber wall. The same pressure, applied to the base of the projectile, causes it to swell or upset, filling and sealing the bore.

Bullet Jacket

Usually a metallic cover over the core of a bullet.

Minie Ball

a conical nosed lead bullet, slightly under bore diameter, incorporating a hollow base, designed to expand into the rifled bore upon firing for gas sealing purposes without the use of a patch.

bullet

a non-spherical projectile for use in a rifled barrel

Axis

a real or an imaginary straight reference line passing through an object and about which the object turns or appears to turn.

Gas Cutting

an erosive effect in a firearm or on the base and/or bearing surface of a bullet caused by the high velocity and high temperature of propellant gases.

Nyclad

an inert nylon jacketing or coating on a lead bullet; a Smith & Wesson original trade name later purchased from Federal Cartridge Corporation.

skid Marks

slippage marks are typically produced by revolvers and have the appearance of widening of the land impressions a their beginning point.

Driving Edge

the driving edge of a bullet fired from a gun with a right twist is the right edge of the land impression, or the left edge of the groove impression. The driving edge of a left twist is the left edge of the land impression the right edge of the groove impression.