Terminal ballistics

Terminal ballistics, a sub-field of ballistics, is the study of the behavior and effects of a projectile when it hits its target.[1] Terminal ballistics is relevant both for small caliber pro- jectiles as well as for large caliber projectiles (fired from artillery). The study of extremely high velocity impacts is still very new and is as yet mostly applied to spacecraft design.

1 General

An early result is due to Newton; the impact depth of any .32 ACP full metal jacket, .32 S&W Long wadcutter, .380 ACP projectile is the depth that a projectile will reach before jacketed hollow point stopping in a medium; in Newtonian mechanics, a pro- jectile stops when it has transferred its momentum to an equal mass of the medium. If the impactor and medium 2.1.1 Target shooting have similar density this happens at an impact depth equal to the length of the impactor. For short range target shooting on ranges up to 50 me- For this simple result to be valid, the arresting medium is ters (55 yd), aerodynamics is relatively unimportant and considered to have no integral shear strength. Note that velocities are low. As long as the bullet is balanced so it even though the projectile has stopped, the momentum is does not tumble, the aerodynamics are unimportant. For still transferred, and in the real world spalling and similar shooting at paper targets, the best bullet is one that will effects can occur. punch a perfect hole through the target. These bullets are called wadcutters. They have a very flat front, often with a relatively sharp edge along the perimeter. The flat front punches out a large hole in the paper, close to, if not equal 2 Firearm projectiles to, the full diameter of the bullet. This allows for easy, unambiguous scoring of the tar- 2.1 Classes of bullet get. Since cutting the edge of a target ring will result in scoring the higher score, fractions of an inch are impor- tant. Magazine-fed pistols may not reliably feed wadcut- There are three basic classes of bullet: ters because of the angular shape. To address this, the semiwadcutter is used. The semiwadcutter consists of a • those designed for maximum accuracy at varying conical section that comes to a smaller flat, and a thin ranges sharp shoulder at the base of the cone. The flat point punches a clean hole, and the shoulder opens the hole up cleanly. For steel targets, the concern is to provide • those designed to maximize damage to a target by enough force to knock over the target while minimizing penetrating as deeply as possible the damage to the target. A soft lead bullet, or a jacketed hollow-point bullet or soft-point bullet will flatten out on • those designed to avoid over-penetration of a target, impact (if the velocity at impact is sufficient to make it by deforming to control the depth to which the bullet deform), spreading the impact over a larger area of the penetrates, which as a by-product, deals more dam- target, allowing more total force to be applied without age inside the wound. damaging the steel target. There are also specialized bullets designed for use in long The third class may limit penetration by expanding or range precision target shooting with high-powered ri- fragmenting. fles; the designs vary somewhat from manufacturer to

1 2 2 FIREARM PROJECTILES

manufacturer, but all are based on the MatchKing bullets customized rifle with an appropriately cut chamber and a introduced by the Sierra Bullet Company around 1963. fast-twist bore. Based on research done in the 1950s by the U.S. Air Force, in which it was discovered that bullets are more stable in flight for longer distances and more resistant to 2.1.2 Maximum penetration crosswinds if the center of gravity is somewhat to the rear of the center of pressure, the MatchKing bullet (which is For use against armored targets, or large, tough game an- still in wide use and holds many records) is a hollow point imals, penetration is the most important consideration. design with a tiny aperture in the jacket at the point of the Focusing the largest amount of momentum on the small- bullet and a hollow air space under the point of the bullet, est possible area of the target provides the greatest pen- where previous conventional bullets had had a lead core etration. Bullets for maximum penetration are designed that went all the way up to the point.[2] to resist deformation on impact, and usually are made of lead that is covered in a copper, brass, or mild steel jacket Other designs from other manufacturers may be anything (some are even solid copper or bronze alloy). The jacket from close copies of the MatchKing design to hollow completely covers the front of the bullet, although often point bullets with a deep, wide cavity containing a long, the rear is left with exposed lead (this is a manufacturing slender, pointed plastic or aluminum plug. In all these consideration: the jacket is formed first, and the lead is cases, the bullet is designed to have its center of gravity swaged in from the rear). to the rear of its center of pressure. MatchKing-type hol- low point bullets, as contrasted with hollow point bullets For penetrating substances significantly harder than jack- intended for hunting or police use, are not designed to eted lead, the lead core is supplemented with or replaced flatten out on impact; this makes them a relatively poor with a harder material, such as hardened steel. Military choice for hunting, as they tend to perform erratically armor piercing small arms ammunition is made from a and unpredictably upon entering an animal’s body—they copper-jacketed steel core; the steel resists deformation may tumble, or break apart, though most often they punch better than the usual soft lead core leading to greater pen- straight through making a narrow wound that usually does etration. The current NATO 5.56mm SS109 (M855) bul- not cause death quickly. The U.S. military now issues let uses a steel tipped lead core to improve penetration, ammunition to snipers that use bullets of this type. In the steel tip providing resistance to deformation for armor 7.62×51mm NATO, M852 Match and M118LR ammu- piercing, and the heavier lead core (25% heavier than the nition are issued, both of which use Sierra MatchKing previous bullet, the M193) providing increased sectional bullets; in 5.56×45mm NATO, those U.S. Navy and U.S. density for better penetration in soft targets. For larger, Marine snipers who use accurized M16-type rifles are is- higher velocity calibers, such as tank guns, hardness is of sued the Mk 262 Mod 0 cartridge developed jointly by secondary importance to density, and are normally sub- Black Hills Ammunition and Crane Naval Surface War- caliber projectiles made from tungsten carbide, tungsten fare Center, using a bullet manufactured by Sierra Bullets hard alloy or depleted uranium fired in a light aluminum that was cannelured according to military specifications or magnesium alloy (or carbon fibre in some cases) sabot. for this project. Many modern tank guns are smoothbore, not rifled be- In 1990, the U.S. Army Adjutant General’s Office issued cause practical rifling twists can only stabilize projectiles, a legal opinion holding that the Sierra MatchKing bullet, such as an armour-piercing fin-stabilized discarding sabot despite being an open-tip design, is not designed specif- (APFSDS), with a length to diameter ratio of up to about ically to cause greater damage or suffering in a human 5:1, the spin imposed by rifling interferes with shaped target, and in fact normally does not create a wound read- charge rounds, and also because the rifling adds friction ily distinguishable from wounds caused by conventional and reduces the velocity it is possible to achieve. To get full metal jacket bullets, and is therefore in their opinion the maximum force on the smallest area, anti-tank rounds legal under the Hague Convention for use in war.[3] have aspect ratios of 10:1 or more. Since these cannot be stabilized by rifling, they are built instead like large darts, For ultra long range precision target shooting with with fins providing the stabilizing force, negating the need high-powered rifles and military sniping, radically de- for rifling. These subcaliber rounds are held in place in signed very-low-drag (VLD) bullets are available that are the bore by sabots. The sabot is a light material that trans- generally produced out of rods of mono-metal alloys on fers the pressure of the charge to the penetrator, then is CNC lathes. The driving force behind these projectiles discarded when the round leaves the barrel. is the wish to enhance the practical maximum effective range beyond normal standards. To achieve this, the bul- lets have to be very long and normal cartridge overall 2.1.3 Controlled penetration lengths often have to be exceeded. Common rifling twist rates also often have to be tightened to stabilize very long The final category of bullets is that intended to control projectiles. Such commercially nonexistent cartridges penetration so as not to harm anything behind the target. are termed “wildcats”. The use of a wildcat based (ul- Such bullets are used primarily for hunting and civilian tra) long-range cartridge demands the use of a custom or antipersonnel use; they are not generally used by the mil- 2.1 Classes of bullet 3 itary, since the use of expanding bullets in international to expand the damaged area. The hollow point fills with conflicts is prohibited by the Hague Convention and be- body water on impact, then expands as the bullet con- cause these bullets have less chance of penetrating mod- tinues to have water pushed into it. This process is called ern body armor. These bullets are designed to increase mushrooming, as the ideal result is a shape that resembles their surface area on impact, thus creating greater drag a mushroom—a cylindrical base, topped with a wide sur- and limiting the travel through the target. A desirable side face where the tip of the bullet has peeled back to expose effect is that the expanded bullet makes a larger hole, in- more area to create more drag while traveling through a creasing tissue disruption and speeding incapacitation. body. A copper-plated hollowpoint loaded in a .44 Mag- num, for example, with an original weight of 240 grains In some applications, preventing exit from the rear of the target is also desirable. A bullet that penetrates through- (15.55 g) and a diameter of 0.43 inch (11 mm) might mushroom on impact to form a rough circle with a diam- and-through tends to cause more profuse bleeding, allow- ing a game animal to be bloodtrailed more easily. On eter of 0.70 inch (18 mm) and a final weight of 239 grains (15.48 g). the other hand, a perforating bullet can then continue on (likely not coaxial to the original trajectory due to target This is excellent performance; almost the entire weight deflection) and might cause unintended damage or injury. is retained, and the frontal surface area increased 63%. Frangible bullets, made of tiny fragments held together by Penetration of the hollowpoint would be less than half a weak binding, are often sold as an “ultimate” expand- that of a similar nonexpanding bullet, and the resulting ing bullet, as they will increase their effective diameter wound or permanent cavity would be much wider. by an order of magnitude. When they work, they work extremely well, causing massive trauma to the target. On the other hand, when they fail, it is due to underpenetra- tion, and the damage to the target is superficial and leads to very slow incapacitation.

Flat point The simplest maximum disruption bullet is one with a wide, flat tip. This increases the effective sur- face area, as rounded bullets can allow tissues to “flow” around the edges. It also increases drag during flight, which decreases the depth to which the bullet penetrates. Older centerfire rifles with tube magazines were designed to be used with flat-point bullets. Flat-point bullets, with Example photo of the over-penetration of a fragmenting projec- fronts of up to 90% of the overall bullet diameter, are tile. usually designed for use against large or dangerous game. They are often made of unusually hard alloys, are longer Fragmenting This class of projectile is designed to and heavier than normal for their caliber, and even in- break apart on impact, causing an effect similar to that clude exotic materials such as tungsten to increase their of a frangible projectile, whilst being of a construction sectional density. more akin to that of an expanding bullet. Fragmenting bullets are usually constructed like the hollowpoint pro- These bullets are designed to penetrate deeply through jectiles described above, but with deeper and larger cav- muscle and bone, while causing a wound channel of ities. They may also have thinner copper jackets in or- nearly the full diameter of the bullet. These bullets are der to reduce their overall integrity. For the purposes designed to penetrate deeply enough to reach vital organs of aerodynamic efficiency the tip of the hollowpoint will from any shooting angle and at a far enough range. One often be tipped with a pointed polymer 'nose'. These of the hunting applications of the flat point bullet is large bullets are typically fired at high velocities to maximize game such as bear hunted with a handgun in a .44 Mag- their fragmentation upon impact. In contrast to a hollow- num or larger caliber. More common than hunting is its point which attempts to stay in one large piece retaining use in a defensive “bear gun” carried by outdoorsmen. as much weight as possible whilst presenting the most sur- The disadvantage of flat point bullets is the reduction in face area to the target, a fragmenting bullet is intended to aerodynamic performance; the flat point induces much break up into many small pieces almost instantly. drag, leading to significantly reduced velocities at long range. This means that all the kinetic energy from the bullet is transferred into the target in a very short space of time. The most common application of this bullet is the shoot- Expanding More effective on lighter targets are the ex- ing of small vermin, such as prairie dogs. The effect of panding bullets, the hollow point bullet and the soft point these bullets is quite dramatic, often resulting in the ani- bullet. These are designed to use the hydraulic pressure mal being blown apart upon impact. However, on larger of muscle tissue to expand the bullet. The hollow point game fragmenting ammunition provides inadequate pen- peels back into eight or nine connected pieces causing it etration of vital organs to ensure a clean kill, instead a 4 2 FIREARM PROJECTILES

“splash wound” may result. This also limits practical use are also known to fragment due to jacket construction. of these rounds to supersonic (rifle) rounds, which have Other bullets in use by militaries are quite back heavy, a high enough kinetic energy to ensure a lethal hit. The due to a long, sharp point created in an attempt to get two main advantages of this ammunition are that it is very the maximum ballistic coefficient (see external ballis- humane, a hit almost anywhere on most small vermin will tics). These bullets will flip over after impact, then settle ensure an instant kill, and that instead of dangerously and into a stable, back first orientation before stopping. The uncontrollably ricocheting off surfaces, the bullet harm- Swiss military actually redesigned their 5.56mm assault lessly breaks apart. Fragmenting bullets should not be rifle bullet to prevent this, to more fully comply with the confused with frangible bullets (See below). spirit of the Hague Convention, though according to some sources the present GP90 5.56×45mm Swiss assault rifle ammunition was actually designed as an armor-piercing Frangible The last category of expanding bullets are bullet, because, in the 1980s, it was perceived that the the frangible bullets. These bullets are designed to break Soviets and their Warsaw Pact allies were going to issue up on impact, which results in a huge increase in surface soft body armor to infantry units on a wide basis, but after area. The most common of these bullets are made of the end of the Cold War, the Bofors corporation, having small diameter lead pellets, placed in a thin copper shell spent a great deal of money on developing the new bul- and held in place by an epoxy or similar binding agent. let, changed the sales pitch in order to sell it to the Swiss On impact, the epoxy shatters and the copper shell opens government. up, much like a hollowpoint. The individual lead balls It might seem that if the whole purpose of a maximum then spread out in a wide pattern, and due to their low disruption round is to expand to a larger diameter, it mass to surface area ratio, stop very quickly. Similar bul- would make more sense to start out with the desired diam- lets are made out of sintered metals, which turn to powder eter rather than relying on the somewhat inconsistent re- upon impact. These bullets are usually restricted to pis- sults of expansion on impact. While there is merit to this tol cartridges, as the nonhomogenous cores tend to cause (there is a strong following of the .45 ACP, as compared inaccuracies that, while acceptable at short pistol ranges, to the .40 S&W and 0.355 in diameter 9×19mm, for just are not acceptable for the typical range at which rifles are this reason) there are also significant downsides. A larger used. diameter bullet is going to have significantly more drag One interesting use of the sintered metal rounds is in shot- than a smaller diameter bullet of the same mass, which guns in hostage rescue situations; the sintered metal round means long range performance will be significantly de- is used at near-contact range to shoot the lock mechanism graded. A larger diameter bullet also means more space out of doors. The resulting metal powder will immedi- is required to store the ammunition, which means either ately disperse after knocking out the door lock, and cause bulkier guns or smaller magazine capacities. The com- little or no damage to occupants of the room. Frangible mon trade-off when comparing .45 ACP, .40 S&W, and rounds are also used by armed security agents on aircraft. 9×19mm pistols is a 7- to 14-round capacity in the .45 The concern is not depressurization (a bullet hole will not ACP vs. a 10- to 16-round capacity in the .40 S&W vs. depressurise an airliner), but over penetration and dam- a 13- to 19-round capacity in the 9×19mm. age to vital electrical or hydraulic lines, or injury to an Although several .45-caliber pistols are available with innocent bystander by a bullet that travels through a tar- high-capacity magazines (Para Ordnance being one of the get’s body completely instead of stopping in the body. first in the late 1980s) many people find the wide grip Also used are bullets similar to hollowpoint bullets or soft required uncomfortable and difficult to use. Especially point bullets whose cores and/or jackets are deliberately where the military requirement of a nonexpanding round weakened to cause deformation or fragmentation upon is concerned, there is fierce debate over whether it is bet- impact. The Warsaw Pact 5.45×39mm M74 assault ri- ter to have fewer, larger bullets for enhanced terminal ef- fle round exemplifies a trend that is becoming common fects, or more, smaller bullets for increased number of in the era of high velocity, small caliber military rounds. potential target hits. The 5.45×39mm uses a steel-jacketed bullet with a two- part core, the rear being steel and the front being lead. Upon impact, the lead deforms, bending the bullet into a 2.2 Selecting for terminal performance slight “L” shape. This causes the bullet to tumble in the tissue, thus increasing its effective frontal surface area by Further information: Stopping power traveling sideways more often than not. This does not violate the Hague Convention, as it specif- The standard medium for testing bullets for performance ically mentions bullets that expand or flatten in the body. on tissue is ballistic gelatin. Tests have shown that prop- The NATO SS109 also tends to bend at the steel/lead erly prepared and calibrated 10% (by mass) gelatin at 4 junction, but with its weaker jacket, it fragments into degrees Celsius correlates very closely to observed per- many dozens of pieces. NATO 7.62 mm ball manufac- formance in the muscle tissue of a living swine. Perfor- tured by some countries, such as Germany and Sweden, mance is generally graded with two factors, the maximum 2.3 Non-military defensive purposes 5 depth of penetration and the size of the cavity formed When hunting deer, a bullet that penetrates deeper is re- in the gelatin by the bullet impact. The size of the cav- quired; this can be accomplished by either limiting expan- ity represents the distance which tissue is thrown radially sion (twice the original width is often regarded as ideal), outward due to “splash.” The penetration represents how or by using a more powerful cartridge. far into the tissue the bullet will ultimately penetrate. For hunting bear, yet more penetration is required. The Unfortunately, improperly prepared gelatin is a poor pattern is, of course, that the larger the animal, the deeper medium for evaluating actual effectiveness. The ob- its vital organs will be located, and therefore a firearm, served “tissue splash”, usually referred to as “temporary cartridge, and bullet type should be chosen that will be cavitation”, is not an indication of terminal performance able to reach the vital organs and kill humanely. in an animal, as gelatin has a much lower elastic limit than For dangerous game, especially deep penetration is crit- most living tissues; a force that tears a gelatin block in half ical; the reason for this is that the shooter cannot always may result in nothing more than slight bruising if applied choose their shots. If a hunter finds himself staring at to living flesh. a deer’s hindquarters, it is very unlikely that he or she Gelatin as a testing medium is greatly misunderstood. will choose to fire at that deer anyway, in the hopes that Temporary cavitation is almost meaningless. Permanent their bullet will be able to reach a vital organ through sev- cavitation is of value, however, as it is the penetration eral layers of muscle and gut. The better choice in that multiplied by the expanded bullet’s diameter. It predicts scenario would be to wait until the deer decides to turn actual tissue damage. The value is knowing what the fi- around. A lion, however, may decide to charge at a per- nal expanded shape of the bullet will be and how deep it son other than the shooter, presenting a much less than will penetrate. That is what the gelatin medium does best. optimal shooting angle. One does not know what the terminal shape of the bul- To hit the vital organs on a large game animal requires let will be until it is actually tested. US Army retired, penetrating the thick fat and muscle tissue surrounding Col Martin Fackler’s, (MD) work was the comparison the chest cavity, and quite often bone as well. A hard, of gelatin performance tests with 200 actual cadavers. nondeforming bullet is often chosen, though many mod- He found that properly prepared gelatin was a reliable ern rifle calibers are quite capable of killing 1,000 lb (450 medium for predicting depth of penetration and bullet de- kg) elk and similar-sized animals with a deforming bul- formation. Big bullets make big holes, heavy bullets make let; even the venerable .30-06 is up to the task, provided deep holes. However, over expanded bullets may not pen- it has a powerful enough load. Elephant hunters normally etrate deeply enough. The point to remember is, place- attempt to shoot for the brain, which is much smaller than ment is the single most important factor in immediate in- the size of the elephant’s head, and so must be targeted capacitation. A bullet must penetrate deeply enough to quite precisely, and requires a firearm and bullet capable reach and damage vital organs, such as the heart. Imme- of punching through a foot (300 mm) or more of tough, diate incapacitation occurs when the central nervous sys- albeit hollow, bone and reaching the brain. tem is interrupted, either by contact damage or by anoxia from blood loss. Even with a punctured heart an assailant can function for about 11 seconds. (Fackler,M.L., M.D., 2.3 Non-military defensive purposes Director, Wound Ballistics Laboratory, Letterman Army Institute of Research, Presidio, San Francisco CA. “Bul- The rules of engagement for non-military use of firearms let Performance Misconceptions” International Defense usually require that a life, or in some jurisdictions, prop- Review 3, 369-370, 1987) erty, must be in immediate danger, for shots to be fired. Penetration figures may not be accurate, as some testers Under such circumstances, the goal is to incapacitate the may not calibrate their gelatin. The standard calibration target as quickly as possible, to prevent the harm from is 85 mm of penetration when shot by a standard .177 cal- being done. In most cases, the shots are fired from a iber steel bb traveling at 180 m/s (590 ft/s). Uncalibrated handgun, which is, compared to a rifle, very much under- gelatin may show a variance of up to + or - 50% from cal- powered. Humans are in roughly the same class as deer ibrated gelatin. Further, animals’ skin resists penetration sized game, and in most places, the minimum cartridge much more than the muscle tissue which gelatin simu- power required to hunt deer is more than twice that of lates. Human skin tissue on the torso resists penetration the average police sidearm. Handguns are also very in- as much as 50 mm (2 in) of muscle, and horses’ skin is accurate in the hands of inexperienced shooters, and the the equivalent of approximately 200 mm (7.9 in). average defensive shooter is under a great deal of stress, which further degrades accuracy. These factors combine For a quick incapacitation, a hit to a vital, blood-bearing to require extremely effective terminal ballistics to pro- organ or the central nervous system is needed, so a bul- vide swift incapacitation of the target under far less than let that will penetrate to the depth required for such a ideal circumstances. hit should be chosen. When hunting groundhogs, for ex- ample, a bullet that expands quickly to form a large cav- Humans walk upright and present relatively unprotected ity with minimum penetration would be the best choice. vital organ targets from some angles, and have substan- tially thinner skin, so the bare minimum penetration is 6 2 FIREARM PROJECTILES

lower than for deer. Cross-torso shots and shots that must be produced. If a bomblet strikes an armoured vehicle, first penetrate an arm are relatively common in defensive there is also a chance that the shaped charge will (if used) shooting scenarios, however. penetrate and disable the vehicle. A negative factor in Bullets for use on humans are usually designed to com- their use is that any bomblets that fail to function go on to ply with the FBI’s penetration requirement of 12 to 18 litter the battlefield in a highly sensitive and lethal state, inches (30 to 46 cm), which is based on the IWBA’s re- causing casualties long after the cessation of conflict. In- quirement of 12.5 to 14 inches (32 to 36 cm). This is to ternational conventions tend to forbid or restrict the use ensure that the bullet can reach a vital blood-bearing or- of this type of projectile. gan or central nervous system structure from most angles. Some anti-armour projectiles use what is known as a Frangible rounds, while they are sold for defensive pur- shaped charge to defeat their target. Shaped charges have poses, are not well suited for the role, as they generally been used ever since it was discovered that a block of high penetrate less than 10 inches (25 cm), and are therefore explosives with letters engraved in it created perfect im- prone to failure when they must pass through nonvital tis- pressions of those letters when detonated against a piece sues, such as a hand or arm. of metal. A shaped charge is an explosive charge with a Hollowpoint bullets normally expand most when at their hollow lined cavity at one end and a detonator at the other. highest velocity; that is, when entering the target. As They operate by the detonating high explosive collapsing they expand, they slow. Hollowpoint bullets may not ex- the (often copper) liner into itself. Some of the collapsing pand when they strike sheet metal, glass, or bulky cloth- liner goes on to form a constantly stretching jet of mate- ing before the target. These preliminary obstacles can rial travelling at hypersonic speed. When detonated at the either fill the hollowpoint cavity or deform the lips of the correct standoff to the armour, the jet violently forces its cavity. Either of these effects can prevent the high in- way through the target’s armour. ternal hydraulic pressure necessary to make the hollow- Contrary to popular belief, the jet of a copper lined point round expand. Some modern hollow-point defen- shaped charge is not molten, although it is heated to about sive rounds have a soft polymer tip to help them pass 500 °C. This misconception is due to the metal’s fluid-like through clothing without being plugged by cloth frag- behaviour, which is caused by the massive pressures pro- ments. duced during the explosives detonation causing the metal For in-depth information on the mechanisms (and mis- to flow plastically. When used in the anti-tank role, a pro- jectile that uses a shaped charge warhead is known by the conceptions) by which bullets incapacitate living targets, see the article on stopping power. acronym HEAT (high explosive anti-tank). Shaped charges can be defended against by the use of explosive reactive armour (ERA), or complex composite 2.4 Large caliber armour arrays. ERA uses a high explosive sandwiched between two, relatively thin, (normally) metallic plates. The explosive is detonated when struck by the shaped The purpose of firing a large calibre projectile is not al- charge’s jet, the detonating explosive sandwich forces the ways the same. For example, one might need to cre- two plates apart, lowering the jets’ penetration by inter- ate disorganisation within enemy troops, create casual- fering with, and disrupting it. A disadvantage of using ties within enemy troops, eliminate the functioning of an ERA is that each plate can protect against a single strike, enemy tank, or destroy an enemy bunker. Different pur- and the resulting explosion can be extremely dangerous poses of course require different projectile designs. to nearby personnel and lightly armoured structures. Many large calibre projectiles are filled with a high ex- Tank fired HEAT projectiles are slowly being replaced plosive which, when detonated, shatters the shell casing, for the attack of heavy armour by so-called “kinetic en- producing thousands of high velocity fragments and an ergy” penetrators. Ironically, it is the most primitive (in- accompanying sharply rising blast overpressure. More shape) projectiles that are hardest to defend against. A rarely, others are used to release chemical or biological KE penetrator requires an enormous thickness of steel, agents, either on impact or when over the target area; de- or a complex armour array to protect against. They also signing an appropriate fuse is a difficult task which lies produce a much larger diameter hole in comparison to outside the realm of terminal ballistics. a shaped charge and hence produce a far more extensive Other large calibre projectiles use bomblets (sub- behind armour effect. KE penetrators are most effective munitions), which are released by the carrier projectile when constructed of a dense tough material that is formed at a required height or time above their target. For US into a long, narrow, arrow/dart like projectile. artillery ammunition, these projectiles are called Dual- Tungsten and depleted uranium alloys are often used as Purpose Improved Conventional Munition (DPICM), a the penetrator material. The length of the penetrator is 155 mm M864 DPICM projectile for example contains limited by the ability of the penetrator to withstand launch a total of 72 shaped charge fragmentation bomblets. The forces whilst in the bore and shear forces along its length use of multiple bomblets over a single HE projectile al- at impact. lows for a denser and less wasteful fragmentation field to 7

3 Hypervelocity currently difficult; light-gas guns are currently the most common techniques for producing such speeds, although The study of projectile impacts with hypersonic velocities linear motors, railguns, coilguns and ram accelerators are greater than several kilometres per second is an area of also possibilities undergoing active research. NASA has active research.[4] been using two-stage light-gas guns to simulate 2.2-cm diameter micrometeoid and orbital debris at velocities in Such impacts are not yet used in military situations— excess of 7.5 km/s for decades[14] and in 2005, Bigelow although active military research in hypersonic weapons Aerospace utilized an earthbound test apparatus firing [5] is going on —but can arise from meteorite impacts on 1.7-cm-diameter aluminum projectiles into its inflatable spacecraft. The impact of extremely small, extremely fast spacecraft multilayer shield technology at 7 km/s.[15] particles is of interest in designing spacecraft to withstand erosion due to micrometeoroids and small orbital debris. 4 See also

• Forensic ballistics

• Gunshot injury

• Hydrostatic shock

• Kinetic energy penetrator

• Stopping power

• Table of handgun and rifle cartridges

• Taylor KO factor

• Vaporific effect

5 References

[1] Terminal Ballistics Test and Analysis Guidelines for the Penetration Mechanics Branch - BRL

[2] Gyroscopic Stability of Open Tipped Match Style Rifle Bullets by ELYA R. COURTNEY AND MICHAEL W. Cut-away view of the multi-layer, Micrometeoroid Orbital Debris COURTNEY (MOD) ballistic-shielding on TransHab.[6] [3] Parks, W. Hays (12 October 1990). “MEMORANDUM Ceramic fiber woven shields offer better protection to FOR COMMANDER, UNITED STATES ARMY SPE- hypervelocity (>2 km/s) particles than aluminum shields CIAL OPERATIONS COMMAND; SUBJECT: Sniper of equal weight,[7] and whipple shields also offer some Use of Open-Tip Ammunition”. The Gun Zone. Re- trieved 23 June 2011. protection from orbital micrometeroids.[8] One design for protection from small space debris and [4] Thompson, Mark (2012-08-27). “Bigelow’s inflatable micrometeroids was the multi-layer shell of NASA's space stations”. SEN. Retrieved 2012-09-09. a mate- TransHab space habitation module.[9] This technology rial called Vectran, twice as strong as Kevlar and present was subsequently licensed by private company Bigelow in several layers of the 15cm thick skin of the Genesis [space]craft. The flexible nature of the material results Aerospace which is pursuing a similar scheme for a [10] in further added safety for potential station inhabitants, private space station design. Two Bigelow inflatable- a benefit supported by laboratory tests. It was found technology space craft, Genesis I and Genesis II, built that micrometeoroids that would puncture the rigid skin of with proprietary extensions of the NASA technology, the International Space Station only penetrated half way were launched in 2006.[11] As of April 2009, both through the skin of the Genesis craft. ... Hypervelocity spacecraft were still operating nominally after more tests conducted by Bigelow Aerospace have shown that this than 10,000 orbits and traveling over 270 million miles, shield provides greater protection than a traditional alu- demonstrating significant real-world validation testing of minium can design. a fabric-based ballistic shield.[12][13] [5] Brendan Borrell (February 6, 2008). “Electromagnetic Accelerating projectiles up to such speeds on earth is Railgun Blasts Off”. Technology Review. 8 6 EXTERNAL LINKS

[6] International Space Station Imagery, image S99-05362, “Computer Generated Still -- Cutaway of the TransHab Module shell showing the various layers,” 2001-08-30

[7] Ceramic Fabric Offers Space Age Protection, 1994 Hy- pervelocity Impact Symposium

[8] , Karen Rodriguez, White Sands Test Facility (WSTF) Re- mote Hypervelocity Test Laboratory (RHTL), Jul 2009.

[9] Kim Dismukes (curator) (2003-06-27). “TransHab Con- cept”. NASA.gov. Retrieved 2007-06-10.

[10] Schrimpsher, Dan (2006-08-21). “Interview: TransHab developer William Schneider”. TheSpaceReview.com. Retrieved 2007-06-10.

[11] Company sees future in space, Las Vegas Review-Journal, 15 Aug 2007, Accessed 3 Oct 2009

[12] Malik, Tariq (2008-05-09). “Private Space Station Pro- totype Hits Orbital Milestone”. Space.com. Retrieved 2009-10-03.

[13] “Genesis II Completes 10,000 Orbits!". BigelowAerospace.com. 2009-04-23. Retrieved 2009-10-03.

[14] , Karen Rodriguez, White Sands Test Facility (WSTF) Re- mote Hypervelocity Test Laboratory (RHTL), Dec 2011.

[15] Putting Up the Ritz: Can pneumatic buildings breathe life into space tourism?, James Oberg, IEEE Spectrum, Feb 2007.

6 External links

• Ballistic gelatin test results & pictures

• Shooting Holes in Wounding Theories: The Me- chanics of Terminal Ballistics

• Shaped charges

• Handgun Wounding Factors and Effectiveness, a 1989 FBI publication 9

7 Text and image sources, contributors, and licenses

7.1 Text

• Terminal ballistics Source: https://en.wikipedia.org/wiki/Terminal_ballistics?oldid=683022711 Contributors: The Anome, Heron, Patrick, Michael Hardy, Gabbe, Karada, Aarchiba, Julesd, Gamma~enwiki, Francs2000, Riddley, Fuelbottle, Iain.mcclatchie, Sho Ue- mura, Buster2058, DocWatson42, Wolfkeeper, Tom harrison, Gracefool, Alvestrand, Bobblewik, Wmahan, Bob.v.R, Grunt, AliveFree- Happy, Deh, Fluzwup, Night Gyr, ZeroOne, Plugwash, Gerweck, Interiot, Hohum, Gene Nygaard, D.E. Watters, Eatsaq, GregorB, Chron- tius, Arrkhal, Mandarax, Sjö, Rangek, Dusty78, WouterBot, Bgwhite, WriterHound, Shaddack, Robotmannick, Fenris78, SmackBot, Reedy, NeilGibson, Chris the speller, Elabro, Arctosouros, OnBeyondZebrax, Crossbow~enwiki, Tawkerbot2, Junglecode, CmdrObot, Apfox, N2e, Nabokov, Thijs!bot, N5iln, Corwin MacGregor, Alangu, Myofilus, Thernlund, Eastsidehastings, Falsedan, LurkingInChicago, J.delanoy, Cannibalicious!, Useight, Deor, Dbooksta, Snowbot, Francis Flinch, Nagy, Michael Courtney, Z-angel~enwiki, Jazzuban, Clue- Bot, Mild Bill Hiccup, Wiki Phantoms, The Founders Intent, Sun Creator, Mdeby, Addbot, Lightbot, NapoleonoftheNow, Yobot, Azure- Fury, AnomieBOT, Quebec99, Xqbot, Halconen, Spongefrog, GliderMaven, LucienBOT, Goodraise1234, ROG5728, LcawteHuggle, John of Reading, Faceless Enemy, GuntherDyckmans, ZéroBot, George Makepeace, ClueBot NG, BG19bot, Glevum, Sgtnichols, Donfbreed2 and Anonymous: 106

7.2 Images

• File:Aimed_Research_Sub-Microsecond_Photography_of_Federal_Power-Shok_100grn_.243.JPG Source: https: //upload.wikimedia.org/wikipedia/commons/5/5f/Aimed_Research_Sub-Microsecond_Photography_of_Federal_Power-Shok_ 100grn_.243.JPG License: CC BY-SA 3.0 Contributors: Own work Original artist: Nathan Boor & Kurt Groover of Aimed Research • File:Ambox_important.svg Source: https://upload.wikimedia.org/wikipedia/commons/b/b4/Ambox_important.svg License: Public do- main Contributors: Own work, based off of Image:Ambox scales.svg Original artist: Dsmurat (talk · contribs) • File:IDET2007_bulletproof_glass_armor.jpg Source: https://upload.wikimedia.org/wikipedia/commons/f/f8/IDET2007_bulletproof_ glass_armor.jpg License: Public domain Contributors: Own work Original artist: Shaddack • File:IDET2007_composite_armor_ballistic_test.jpg Source: https://upload.wikimedia.org/wikipedia/commons/c/c0/IDET2007_ composite_armor_ballistic_test.jpg License: Public domain Contributors: Own work Original artist: Shaddack • File:IDET2007_penetrated_armor_plate.jpg Source: https://upload.wikimedia.org/wikipedia/commons/6/6a/IDET2007_penetrated_ armor_plate.jpg License: Public domain Contributors: Own work Original artist: Shaddack • File:IDET2007_steel_armor_plate.jpg Source: https://upload.wikimedia.org/wikipedia/commons/d/d3/IDET2007_steel_armor_plate. jpg License: Public domain Contributors: Own work Original artist: Shaddack • File:Question_book-new.svg Source: https://upload.wikimedia.org/wikipedia/en/9/99/Question_book-new.svg License: Cc-by-sa-3.0 Contributors: Created from scratch in Adobe Illustrator. Based on Image:Question book.png created by User:Equazcion Original artist: Tkgd2007 • File:Text_document_with_red_question_mark.svg Source: https://upload.wikimedia.org/wikipedia/commons/a/a4/Text_document_ with_red_question_mark.svg License: Public domain Contributors: Created by bdesham with Inkscape; based upon Text-x-generic.svg from the Tango project. Original artist: Benjamin D. Esham (bdesham) • File:TransHab_shell_cutaway.jpg Source: https://upload.wikimedia.org/wikipedia/commons/5/53/TransHab_shell_cutaway.jpg Li- cense: Public domain Contributors: http://web.archive.org/web/20020203112011/spaceflight.nasa.gov/gallery/images/station/transhab/ html/s99_05362.html (image link) Original artist: NASA • File:Wadcuttercomp.jpg Source: https://upload.wikimedia.org/wikipedia/commons/2/27/Wadcuttercomp.jpg License: CC BY 2.5 Con- tributors: Own work Original artist: Own work

7.3 Content license

• Creative Commons Attribution-Share Alike 3.0