The LPH Companion, FIREARMS, Part 3: Ammunition

This is the third in a series of articles on firearms with specific reference to the Firearms syllabus of the Learner Hunters/Guides exams. The topics to be covered in separate posts are:

Part 1 – Safety and Firearms

Part 2 – Types of Firearm & the Parts of a Firearm

Part 3 – Ammunition

Part 4 – Ballistics

Part 5 – The Use of Firearms

Part 6 – Purchase and Care of Firearms

Part 7 – Firearms & the Law

AMMUNITION

In this section we will be discussing a wide variety of subjects related to ammunition, ammunition vocabulary, types of ammunition, materials, shape and performance characteristics.

In this section we will be discussing a wide variety of subjects related to ammunition, ammunition vocabulary, types of ammunition, materials, shape and performance characteristics.

Cartridges or Rounds

A cartridge or round is a complete unit of assembled ammunition.  There are two main types of ammunition for firearms, for shotgun and rifle/handguns.

In a shotgun cartridge, the projectile(s) are designed to be fired from a shotgun. The cartridge body is generally made of plastic with a metal base, but may be made of paper or cardboard.

In rifle and handgun ammunition, the cartridge case is made up of metal (usually brass) which contains the gun powder and grips the bullet.

Shotgun Ammunition

In the case of a shotgun, a round comprises the shot, wad, cartridge case, primer and gun powder.

Crimp – seals all components tightly inside the hull. May be 6 or 8 point.

Hull – outer case that holds the components. May be plastic or paper.

Wad – confines powder for uniform ignition and separates powder from shot. (The wad most often used is a one-piece shot cup and wad called a “wad column”.)

Base – holds primer and securely anchors shell in gun breech. May be brass or steel.

Primer pocket – opening in metal base into which primer is inserted.

Shot – Comes in variety of sizes and types for different shooting situations.

Shot Cup – plastic cup holding shot in the pattern as it leaves gun muzzle.

Powder charge – when ignited by primer, powder charge, burning at a controlled rate, generates gas pressure which, with the aid of wad column, propels shot out of the gun barrel.

Primer – Gun firing pin detonates component in primer, which ignites the main powder charge.

Rifle or Handgun Cartridges

Rifle or handgun cartridge consists of the following parts:

• Cartridge case
• Bullet
• Gun powder or propellent
• Primer

These labels are explained more fully below.

Cartridge Case – a metal (usually brass) case which contains the primer and gun powder and grips the bullet.

Primer – a small metal case containing the detonating mixture used to ignite the propellent.

Flash hole – a hole leading from the primer pocket to the inside of the case, through which the spark caused by the detonation mixture can ignite the gun powder.

Bullet – the projectile part of the round, shaped or composed differently for a variety of purposes.

Gun Powder – the propellent material used in most firearms, rated according to burning speed and produced in a variety of types and brands, intended for specific applications. (There are two types of gun powder: smokeless and black gun powder – see notes below)

Crimp – the bending inward of the mouth of the case, in order to grip the bullet or close the mouth of shell-case.

Anvil – the priming system, the fixed metallic point against which the priming mixture is crushed and detonated by the action of the firing pin.

Seating Depth – the length of the bullet head contained by the cartridge’s neck.

The Cartridge Case

The cartridge case is the part of a cartridge which houses the primer, propellant and bullet. It is made of brass or a brass base and cupboard tube. In some cases, the base of the cartridge projects as a rim, ensuring that it does not move forward into the barrel on closing the weapon. In other cases, a bolt or a shoulder will prevent this forward movement.

Cartridge Case Rims

Rimless – the same diameter base flange and case-head. The rim does not protrude but it is grooved into the case-head (e.g. .308, .404 Jeffreys, 8 mm Mauser).

Rimmed – has a base flange, so the rim protrudes beyond the body of the case (e.g. 12 gauge shotguns, .30, .22). This rim is used for head-spacing and extraction.

Belted – has a raised band around the base which is hooked onto during extraction. It is designed for head-spacing and the “belt” is not there to reinforce the case. Usually heavy calibre ammunition (e.g. .375, .458, .300 Winmag).

Semi-rimmed – appears rimless at first glance, but the rim protrudes marginally beyond the case body (e.g. .25, .32 pistols, .220 swift).

Rebated – has a body whose diameter is greater than its rim diameter or, to put it another way, the rim and case are smaller in diameter than the body. An unusual and seldom encountered design (e.g. .425 Wesley Richards).

Centerfire versus Rimfire in Cartridge Cases

Cartridge cases may also be distinguished by the place where the primer is located. The two types are centerfire and rimfire.

• Centerfire – ammunition with a centrally located primer, containing the primer mixture at the base of the cartridge. It is reloadable under normal conditions.
• Rimfire – primer compound is located within the rim of cartridge case. This type of cartridge is not reloadable under normal conditions.

“Head-space” in Cartridges

The head-space is the distance from those surfaces of the barrel or chamber that position the cartridge and prevent its further forward movement into the chamber. In other words, head-space is the distance from the base of the cartridge to the face of the bolt, when the bolt is locked in the firing position.

The following picture shows different types of head-space in cartridges.

Some of the same information is repeated in the diagram below.

It is important to understand head-space because it can be a source of technical problems with a firearm.  Head-space can be too little (insufficient) or too much (excessive):

Signs of Excessive Head-Space

Signs of Insufficient Head-Space:

• Bolt or barrel (in hinged action) difficult to close.
• Round cannot be chambered.
• If round is chambered you will have hard extraction.

“Controlled Feeding” of Cartridges

In controlled feeding, the extractor grabs onto the cartridge and guides it into the chamber. This system makes it possible to extract the cartridge before it has been fully chambered.

The Bullet

The bullet is the foremost part of the round, that becomes a projectile. N.B. It is not a projectile until is in motion. It consists of solid hardened lead, or, in modern ammunition, a core of lead covered by a jacket of tough cupro-zinc (gliding metal), coated steel or brass. The bullet is held in the case by a grooved indentation around the neck (called the cannelure).

The following parts can be recognized in a bullet (explained below):

Heel – the edge of the base of a bullet.

Ogive – the curved or elliptic surface on the front of a bullet, ahead of the bearing surface.

Cannelure – groove around a bullet, used to hold lubricant or to crimp the case into and sometimes for identification.

Bearing surface – portion of the projectile that comes into contact with the bore as the bullet moves through the barrel.

Core – interior part of a jacketed bullet, usually made up of a lead alloy.

Metplate – flat nose of a bullet.

Types of Bullet

Solid bullets

This bullet may be either monolithic (made of a single piece of metal) or heavily jacketed with a lead core. In hunting, it is generally a round-nosed, fully jacketed bullet, used for heavy dangerous game, and gives deep penetration with no expansion.

The core makes up the bulk of the bullet mass and size. The jacket is made from steel with a copper-coat to reduce friction and excessive wear of the barrel.

Solid bullets are designed for Big Game, and especially thick-skinned dangerous animals, to ensure their vital organs (including the brain) are reached with a single shot. They are designedto stay on course, to penetrate deeply and maintain direction through bone.

Monolithic bullets

A monolithic bullet is similar to the solid bullet but is constructed from a one solid material (with no separate jacket and core) typically copper or a copper-zinc brass alloy. It is usually made of lathe-turned brass and is designed for use against thick-skinned animals. It achieves good straight-line penetration through thick skin and heavy bones and has the ability to remain on course and to reach vital organs (e.g. brain) through dense bones.

Full Metal Jacket Bullet (or FMJ)

This is a fully jacketed military design of bullet with a tungsten insert (not lead). They are considered a non-expanding bullet.  They are pointed like boat-tailed bullets and so they have a very high ballistic coefficient. They are designed for long range shooting. This bullet normally tumbles on impact, thereby limiting penetration and they are not suitable for hunting.

Soft-nosed Bullets (or SN)

A soft-nosed bullet is jacketed. The jacket is made of a copper alloy, known as “gilding metal”, which surrounds the lead core. The jacket is open at one end, with the lead core exposed at the tip. This structure is to allow internal expansion during flight and the expansion of the front of the bullet on impact. The bullet is designed to expand or “mushroom” when it strikes an animal.

Controlled Expansion Bullets

Controlled Expansion bullets are designed to stay in one piece despite high-speed impact and only to expand 1 ½ to 2 times of the calibre. This is usually achieved by a partial jacketing of the expanding bullet.  The limited expansion reduces the frontal area friction and helps them to pass through thick animal skin and bones. Controlled Expansion bullets are normally used on thick-skinned animals.

Types of Bullet Point

Bullets are shaped for a variety of purposes.

• Round nose – the end of the bullet is blunt.
• Hollow point – there is a hole in the fore-end of the bullet that creates expansion when a target is struck, creating maximum damage.
• Jacketed – the soft lead showing at the tip is surrounded by another metal, usually copper, that allows the bullet to penetrate a target more easily.
• Wadcutter – the front of the bullet is flattened.
• Semi-wadcutter – intermediate between round-nose and wad-cutter, sometimes incorrectly called a slug or round.

Bullet Weight

This is the mass of the bullet and it is measured in grains [Gr]. 1 [Gr] = 0.065 [g]            1[g] = 15 [Gr]

Abbreviations for Bullet Construction

Bullets are usually identified by abbreviations, which tell you the type of bullet.

Below is a list of some of the more common abbreviations with the manufacturers name where applicable.

BP = Bronze Point (Remington)

CPE = Copper Point Expanding

FP = Full Patch

HBWC = Hollow Base Wad-Cutter

HSP = Hollow Soft Point

JHP = Jacked Hollow Point (Super Vel)

JSP = Jacketed Soft Point

KK = Kopper Klad (Super Vel)

KKSP = Kling Kore Soft-Point (CIL)

L = Lead

Lu = Lubricated MAT = Match

MC = Metal Case

N = Noster Partition Jacket

OPE = Open Point Expanding (Hollow Point)

PCL -= Pointed Core-Lockt (Remington)

PL = Power-Lockt (Remington)

PP = Power-Point (Winchester)

PSP = Pointed Soft Point

SPBT = Soft Point Boat Tail

SM = Starkmantel

SP = Soft Point

SPRN = Soft-Point Round-Nose

ST = Silver Tip (Winchester)

SWC = Semi Wad-Cutter

TOSTO = Vom Hofe Torpedo Stop Ring

TIG = Torpedo Ideal Geschoss

TUG = Torpedo Universal Geschoss

H&H = Holland & Holland

Rem = Remington

Win = Winchester

Gas Checked Bullets

A gas check is a groove around the circumference of a cast bullet which has lubricant in it to stop gasses escaping past the sides  of the bullet. The lubricant acts like a seal in a piston. It may also be a copper cup on the bottom of the cast bullet, used for the same purpose.

The Primer

The primer fits into a hollow of the base of the cartridge case. It is usually a small metal case containing the detonating mixture (lead oxide) used to ignite the priming compound or propellent by the pressure generated by the sudden blow of the firing pin against the anvil.

As mentioned above primer can be centre-fire (located in the centre of the cartridge base) or rim-fire (located within the rim of the cartridge base).

Types of Primer

There are two types of primer, Boxer and Berdan.

• Boxer – the most common primer type. The case has one ignition hole (flash hole) and anvil is self-containing the primer.
• Berdan – has no anvil and the case has two flash-holes. (These are mostly European manufactured).

The Propellent

The propellent material used in most firearms is gunpowder.  It is rated according to burning speed and it is produced in a variety of types, forms and brands, intended for specific applications.

There are two type of gun powder, black and smokeless.

Black Powder

Black powder is the earliest known chemical explosive, developed by the Chinese in the 9^th Century A.D. It consists of a mixture of sulphur, carbon (in the form of charcoal), and saltpeter (potassium nitrate) . The sulphur and carbon act as fuels while the saltpeter is an oxidizer.

Disadvantages of Black powder:

1. Powder compaction and loose bullets – especially in large bore rifles when the magazine in not emptied when shooting, the cartridge remaining and the bullet pushed back into the case by the recoil and result overcoming inertia on the magazine. This causes the bullet to loosen and the powder to get compacted or caked and compressed. (This is why it is important to rotate ammunition – see note below).
2. Produces large clouds of grey smoke that obstruct the shooter visual.

Advantage of Black powder:

It is extremely cheap.

Smokeless Powder

Smokeless Powder is so-called because it does not produce smoke at the muzzle, hence it has an advantage in that it does not interfere with the vision of the shooter.  It is mainly composed of nitrocellulose, with a percentage of other compounds to control burning and prevent premature detonation. It comes in various forms:

• Single base powder – composed of nitrocellulose, usually tubular-shaped grains.
• Double base powder – containing a percentage of nitro-glycerine, usually flake-shaped grains.
• Multi base powder – other organic nitrates, usually ball-shaped grains.

Smokeless Powder is produced in two types, Fast Powder and Slow Powder.

• Fast powder – used for light bullet in short barrel at low velocity (e.g. pistols).
• Slow powder – used in long barrel rifle, in large quantity for high velocity.

Nitrocellulose/Glycerin Propellent

Nitrocellulose/Glycerin Propellent is non-explosive stable but combustible gun powder used in cartridges. It is ignited by a primer at the base of the cartridge when it explodes.

Cycling Ammunition

All ammunition must be regularly checked and cycled. Check that each round is clean and undamaged, that the bullet head is fitted tightly in the cartridge case and the primer of each round is intact.

Cycle the ammunition through the action to ensure that all rounds feed and extract properly. This must be done outdoors. When clearing your magazine of ammunition by working it through the action, you should lock the bolt handle down. Muzzle safety is critical.

Caliber Conversion

Conversion factor: 1 inch = 25.4 mm

Other Ammunition Notes

Magnum

A cartridge with greater power than the average cartridge. A Magnum (Mag) case is usually longer or may have exceptional powder content in relation to the bullet (e.g. .264 Winchester Mag)

Wildcat

A customized round, usually not produced in large quantity.

.30-06

A FMJ corresponding to 7.62 mm

.40-70

Often called “40/70 Government” is a US calibre corresponding to .458