Wound and terminal ballistics

Introduction

The ultimate objective of any weapons system is to deliver a payload to the intended target. If you fail in that objective, then you may as well not have the weapon at all. In the case of rockets, motors, and artillery ammunition, the payload is generally a chemical one (i.e. explosives).

In the case of smallarms (hand held weapons) the payload is usually just the projectile itself - the kinetic energy is delivered to the target. Smallarms include rifles, pistols and shotguns. Rifles and pistols usually deliver only one large projectile, whilst shotguns usually deliver a large number of smaller projectiles. A vast range of shotgun ammunition is available.

There are general widespread misconceptions as to the effectiveness of these smallarms - against both soft and hard targets. These misconceptions have arisen primarily because of the exaggerated weapon performance depicted in most movies and TV shows. Sometimes people just misinterpret scientific data and get the wrong idea when it comes to weapon performance. There are physical limitations as to what you can achieve with hand held weapons.

Note that the term 'soft target' refers to living creatures, and the term 'hard target' refers to vehicles, walls, and the like.

Overview Lethality (soft targets) This is one of the most frequently debated, and most contentious, issues in ballistics. The study of firearm lethality and injuries is generally referred to as 'wound ballistics'. The overview presented here is a simplified explanation of the principles involved - this is a large subject area (primarily by virtue of the fact that there are so many differing opinions, and practical scientific research data is so rare). The criteria generally mentioned when wound ballistics is debated are: * Bullet weight * Bullet design (soft point, hollow point etc) * Velocity * Penetration * Kinetic energy The author has reviewed data relating to many animal tests (pigs & sheep), wounds to military personnel, and wounds to civilians. These wounds were caused by many different calibers; and included rifles, handguns, and shotguns. The author has concluded that (in broad terms) the key criteria for lethality are penetration and kinetic energy. Basically, a bullet must penetrate the target deeply enough to reach vital structures / organs; and it requires kinetic energy to do damage to those structures. If a bullet penetrates the body completely, then any residual kinetic energy is wasted - carried downrange with the bullet. Penetration can be controlled to some extent by bullet design. In handguns the bullets are designed with a hollow cavity in the tip (jacketed hollow point - JHP). This cavity is intended to cause the bullet to expand, on impact, to several times it normal cross-sectional area � the greater resistance caused by the larger frontal area slows the bullet and reduces wasteful, and potentially dangerous, over-penetration. A rifle bullet can be designed with either a soft point (jacketed soft point - JSP) or a hollow point (jacketed hollow point - JHP), and these are intended to expand and/or fragment during penetration, thereby maximizing energy transfer to the target. Military ammunition designers are constrained by the Hague convention, which forbids the use of soft point. hollow point, or frangible bullets in warfare. The designers have worked around the rules (accidentally ?) by using a number of methods such as deep grooves around the periphery of bullets, and hybrid steel/lead cores. The grooves are billed as crimping grooves, intended to help retain the bullet in the cartridge case; however, upon impact they tend to cause the bullets to break up in the target, thereby maximizing energy transfer and wounding effects. The steel cores in some bullets are often cited to be there to give an armor piercing capability. However, they also tend to make the bullet less stable when it enters the more dense media of the body tissues; this causes the bullet to tumble, and once again maximizes energy transfer and wounding effects. Shotguns are widely believed to be very lethal, and at close range this is certainly true because the multiple projectiles cause multiple wound tracks over a small area � often resulting in one large hole. However, the pellets must be large enough so that each one has sufficient kinetic energy to penetrate to vital areas. Basically, bird shot (7 1/2, for example) can only be guaranteed to be lethal to a range of about 5 yards, beyond 10 yards, or so, the wounds may look severe, but be relatively superficial due to the lack of penetration of individual pellets. Large buckshot pellets will be lethal at considerable range, but practical accuracy, and excessive spread, will limit their effective range to around 40 to 60 yards, depending upon choke and individual weapon characteristics. Those who choose to cut down their shotgun barrel diminish lethality considerably, because they may reduce the overall kinetic energy delivered by a given cartridge by as much as 50%. Figure 1 shows a human arm which was injured by a 12 gage shotgun at just 10 yards. The shot size was #6, and the shotgun barrel had been sawn down (length not known, but probably around 14"). Note that pellets are spread over a large area (cartridge contained almost 400) and that they had insufficient energy to penetrate much below the surface of the skin - the silver pellets are visible . Click on the image to see the full size version
	Figure 1 - 12 gage shotgun blast to arm. Range 10 yards, #6 shot
Penetration (hard targets) Penetration potential is also over rated with many weapons. Stories abound of how 12 gage rifled slugs, or 44 magnum handguns, will shatter the engine block of a vehicle, or how an M16 will cut down a tree. The reality is very different, those who've tried their 44 magnum handgun against an engine block are disappointed - it usually leaves only a slight gray mark ! Movies frequently show shotguns making large holes in walls and doors at considerable range - once again vastly over-rated performance. The Ford Escort in Figure 2 was shot from a range of 6 yards using a sawn off shotgun (12" barrel) loaded with #6 shot. Note that a good proportion of the pellets (about 1/3) are in a 6" circle in the center of the pattern - but the remaining 200+ pellets are spread over a wider area. Many people believe that shotgun spread is one inch per yard - in reality a shotgun with no choke (and / or passing through an obstacle) will have an extreme spread in the region of one inch per foot of range. Click on the image to see the full size version
	Figure 2 - 12 gage shotgun blast to Ford Escort. Range 6 yards, #6 shot Note the very wide extreme spread of the pellets (some are outside the perimeter of the photograph). Note also that none of the pellets penetrated the metal - perhaps Fords really are bullet proof !