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Bullets for Beginners

The ultimate goal of all weapons systems is to destroy the target. One of the basic properties by which a weapon's effectiveness is measured is the quantity of energy, and thus damage potential, it delivers to the target. Modern weapons use both kinetic and potential energy systems to achieve maximum lethality. Kinetic energy systems rely on the conversion of kinetic energy (1/2 MV2) into work, while potential energy systems use explosive energy directly in the form of heat and blast or by accelerating the warhead case fragments to increase their kinetic energy and damage volume.

A chemical explosive is a compound or mixture which, upon the application of heat or shock, decomposes or rearranges with extreme rapidity, yielding much gas and heat. Explosives are classified as low or high explosives accord-ing to their rates of decomposition. Low explosives burn rapidly (or deflagrate). High explosives ordinarily deton-ate. There is no sharp line of demarcation between low and high explosives. The chemical decomposition of an explosive may take years, days, hours, or a fraction of a second. The slower forms of decomposition take place in storage and are of interest only from a stability standpoint. Of more in-terest are the two rapid forms of decomposition, burning and detonation. The term "detonation" is used to describe an explosive phenomenon of almost instantaneous decomposition. The properties of the explosive indicate the class into which it falls. In some cases explosives may be made to fall into either class by the conditions under which they are initiated. For convenience, low and high explosives may be differentiated in the following manner.

• Low Explosives are normally employed as propellants. They undergo autocombustion at rates that vary from a few centimeters per second to approximately 400 meters per second. Included in this group are smokeless powders and pyrotechnics such as flares and illumination devices.
• High Explosives are normally employed in warheads. They undergo detonation at rates of 1,000 to 8,500 meters per second. High explosives are conventionally subdivided into two classes and differentiated by sensitivity:
  • Primary. These are extremely sensitive to shock, friction, and heat. They will burn rapidly or detonate if ignited.
  • Secondary. These are relatively insensitive to shock, friction, and heat. They may burn when ignited in small, unconfined quantities; detonation occurs otherwise.

The basic function of any weapon is to deliver a destructive force on an enemy target. Targets of today include military bases, factories, bridges, ships, tanks, missile launching sites, artillery emplacements, fortifications, and troop concentrations. Since each type of target presents a different physical destruction problem, a variety of general and special-purpose warheads are required, within the bounds of cost and logistical availability, so that each target may be attacked with maximum effectiveness.

The gas that causes the pressure that propels the projectile is generated by the ignition of an explosive train. This explosive train is termed a propellant train and consists primarily of low explosives instead of high explosives and has a primer, an igniter or igniting charge, and a propelling charge. Ignition of a small quantity of sensitive explosive, the primer (lead azide), is initiated by a blow from the firing pin and is transmitted and intensified by the igniter so that the large, relatively insensitive propelling charge burns in the proper manner and launches the projectile.

Gunpowders or smokeless powders are the propellants in use today. This substance is produced by combining nitrocellulose (nitric acid and cotton) with ether and alcohol to produce a low explosive. Although called smokeless powders, they are neither smokeless nor in powder form, but in granule form. Smokeless powders may be considered to be classed as either single or multibase powders.

In single-base powders, nitrocellulose is the only explosive present. Other ingredients and additives are added to obtain suitable form, desired burning characteristics, and stability. The standard singlebase smokeless powder used by the Navy is a uniform colloid of ether-alcohol and purified nitrocellulose to which, for purposes of chemical stability, is added a small quantity of diphenylamine.
The multibase powders may be divided into double-base and triple-base powders, both of which contain nitroglycerin to facilitate the dissolving of the nitrocellulose and enhance its explosive qualities. The nitroglycerin also increases the sensitivity, the flame temperature, burning rate, and tendency to detonate. The higher flame temperature serves to decrease the smoke and residue, but increases flash and gun-tube erosion. Double-base propellants have limited use in artillery weapons in the United States due to excessive gun-tube erosion, but are the standard propellants in most other countries. Double-base propellants are used in the United States for mortar propellants, small rocket engines, shotgun shells, the 7.62-mm NATO rifle cartridge, recoilless rifles, and the Navy's 5"/54-caliber gun.
Triple-base propellants are double-base propellants with the addition of nitroguandine to lower the flame temperature, which produces less tube erosion and flash. The major drawback is the limited supply of the raw material nitroguandine. At present, triple-base propellants are used in tank rounds and are being tested for new long-range artillery rounds.

Case guns which fire fixed ammunition employ propellant encased in a metal shell to which the projectile is attached, while bag guns employ propellant charges packed in silk bags. The use of bags is confined to large guns where the total propellant powder required to attain the required initial projectiles velocity is too great in weight and volume to be placed in a single rigid container. By packing the powder grains in bags, it is possible to divide the total charge into units that can be handled expeditiously by one man.

Storage and compatibility groups (CGs)

In view of ammunition and explosives storage principles and the considerations for mixed storage, ammunition and explosives are assigned to the appropriate one of 13 CGs (A through H, J, K, L, N, and S).

1. Group A. Initiating explosives. Bulk initiating explosives that have the necessary sensitivity to heat, friction, or percussion to make them suitable for use as initiating elements in an explosive train. Examples are wet lead azide, wet lead styphnate, wet mercury fulminate, wet tetracene, dry cyclonite (RDX), and dry pentaerythritol tetranitrate (PETN).

2. Group B. Detonators and similar initiating devices not containing two or more independent safety features. Items containing initiating explosives that are designed to initiate or continue the functioning of an explosive train. Examples are detonators, blasting caps, small arms primers, and fuzes.

3. Group C. Bulk propellants, propelling charges, and devices containing propellant with or without their means of ignition. Items that upon initiation will deflagrate, explode, or detonate. Examples are single-, double-, triple-base, and composite propellants, rocket motors (solid propellant), and ammunition with inert projectiles.

4. Group D. Black powder, HE, and ammunition containing HE without its own means of initiation and without propelling charge, or a device containing an initiating explosive and containing two or more independent safety features. Ammunition and explosives that can be expected to explode or detonate when any given item or component thereof is initiated except for devices containing initiating explosives with independent safety features. Examples are bulk trinitrotoluene (TNT), Composition B, black powder, wet RDX or PETN, bombs, projectiles, cluster bomb units (CBUs), depth charges, and torpedo warheads.

5. Group E. Ammunition containing HE without its own means of initiation and containing or with propelling charge (other than one containing a flammable or hypergolic liquid). Examples are artillery ammunition, rockets, or guided missiles.

6. Group F. Ammunition containing HE with its own means of initiation and with propelling charge (other than one containing a flammable or hypergolic liquid) or without a propelling charge.

7. Group G. Fireworks, illuminating, incendiary, and smoke, including hexachlorethane (HC) or tear producing munitions other than those munitions that are water activated or which contain WP or flammable liquid or gel. Ammunition that, upon functioning, results in an incendiary, illumination, lachrymatory, smoke, or sound effect. Examples are flares, signals, incendiary or illuminating ammunition, and other smoke or tear producing devices.

8. Group H. Ammunition containing both explosives and WP or other pyrophoric material. Ammunition in this group contains fillers which are spontaneously flammable when exposed to the atmosphere. Examples are WP, plasticized white phosphorus (PWP), or other ammunition containing pyrophoric material.

9. Group J. Ammunition containing both explosives and flammable liquids or gels. Ammunition in this group contains flammable liquids or gels other than those which are spontaneously flammable when exposed to water or the atmosphere. Examples are liquid- or gel-filled incendiary ammunition, fuel-air explosive (FAE) devices, flammable liquid-fueled missiles, and torpedoes.

10. Group K. Ammunition containing both explosives and toxic chemical agents. Ammunition in this group contains chemicals specifically designed for incapacitating effects more severe than lachrymation. Examples are artillery or mortar ammunition (fuzed or unfuzed), grenades, and rockets or bombs filled with a lethal or incapacitating chemical agent (see note 4, Table 3-1).

11. Group L. Ammunition not included in other compatibility groups. Ammunition having characteristics that do not permit storage with other types of ammunition, or kinds of explosives, or dissimilar ammunition of this group. Examples are water-activated devices, prepackaged hypergolic liquid-fueled rocket engines, certain FAE devices, triethyl aluminum (TEA), and damaged or suspect ammunition of any group. Types presenting similar hazards may be stored together but not mixed with other groups.

12. Group N. Hazard Division 1.6 ammunition containing only extremely insensitive detonating substance (EIDS). Examples are bombs and warheads. If dissimilar Group N munitions, such as Mk 82 and Mk 84 Bombs, are mixed together and have not been tested to assure non-propagation; the mixed munitions are considered to be Hazard Division 1.2, Compatibility Group D for purposes of transportation and storage.

13. Group S. Ammunition presenting no significant hazard. Ammunition so packaged or designed that any hazardous effects arising from accidental functioning are confined within the package unless the package has been degraded by fire, in which case all blast or projection effects are limited to the extent that they do not hinder firefighting significantly. Examples are thermal batteries, explosive switches or valves, and other ammunition items packaged to meet the criteria of this group.

To ease identification of hazard characteristics and thus promote safe storage and transport of ammunition and explosives, the Department of Defense shall use the international system of classification devised by the United Nations Organization (UNO) for transport of dangerous goods. Ammunition and explosives also will be assigned the appropriate Department of Transportation (DOT) class and marking in accordance with 49 CFR 173 (reference (c)).

The UNO classification system consists of nine hazard classes, two of which are applicable to ammunition and explosives as defined in this Standard, Classes 1 and 6, (See ST/SG/AC.10/1/Rev. 9 (reference (d))). Thirteen compatibility groups are included for segregating ammunition and explosives on the basis of similarity of characteristics, properties, and accident effects potential.

Class 1 is divided into divisions that indicate the character and predominance of associated hazards:

Mass-detonating (Division 1).

Non-mass detonating fragment producing (Division 2).

Mass fire (Division 3).

Moderate fire-no blast (Division 4).

Very insensitive explosives (Division 5).

Extremely insensitive ammunition (Division 6).

This Standard uses the term "Hazard Division" instead of "Division", both to emphasize the correspondence with the previous term "Hazard Class" and to avoid the cumbersome alternatives "Division 1 of Class 1," and so forth. For further refinement of this hazard identification system, a numerical figure (in parenthesis) is used to indicate the minimum separation distance (in hundreds of feet) for protection from debris, fragments, and firebrands when distance alone is relied on for such protection. This number is placed to the left of the Hazard Division designators 1.1 through 1.3, such as (18)1.1, (08)1.2, and (02)1.3.

Articles that contain riot control substance without explosives components are classified as Class 6, Division 1, in the UNO Recommendations for Transport of Dangerous Goods. For DoD purposes, these articles are considered as Hazard Division 1.4 and may be stored in limit quantities with other base defense munitions. Bulk agent is also Hazard Division 6.1 in the UNO recommendations.

Sources and Resources

• Fundamentals of Naval Weapons Systems
• DOD AMMUNITION AND EXPLOSIVES SAFETY STANDARDS DOD 6055.9-STD DEPARTMENT OF DEFENSE Under Secretary of Defense for Acquisition and Technology August 1997
• APPENDIX D TEXTS/MANUALS Ordnance and Explosive Waste Archives Search Report for Camp McCain, Mississippi

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