Hollow point bullet
Overview
 
A hollow point is an expanding bullet that has a pit or hollowed out shape in its tip, generally intended to cause the bullet to thin upon entering a target in order to decrease penetration and disrupt more tissue
Tissue (biology)
Tissue is a cellular organizational level intermediate between cells and a complete organism. A tissue is an ensemble of cells, not necessarily identical, but from the same origin, that together carry out a specific function. These are called tissues because of their identical functioning...

 as it travels through the target. It is also used for controlled penetration, where over-penetration could cause collateral damage
Collateral damage
Collateral damage is damage to people or property that is unintended or incidental to the intended outcome. The phrase is prevalently used as an euphemism for civilian casualties of a military action.-Etymology:...

 (such as on an aircraft). In essence, the hollow point bullet has two interrelated purposes: to increase its size once within the target, thus maximizing tissue damage and blood loss or shock, and by remaining in the target to expend all of its kinetic energy in the target, some of which will be lost if the bullet continues through the target.
Encyclopedia
A hollow point is an expanding bullet that has a pit or hollowed out shape in its tip, generally intended to cause the bullet to thin upon entering a target in order to decrease penetration and disrupt more tissue
Tissue (biology)
Tissue is a cellular organizational level intermediate between cells and a complete organism. A tissue is an ensemble of cells, not necessarily identical, but from the same origin, that together carry out a specific function. These are called tissues because of their identical functioning...

 as it travels through the target. It is also used for controlled penetration, where over-penetration could cause collateral damage
Collateral damage
Collateral damage is damage to people or property that is unintended or incidental to the intended outcome. The phrase is prevalently used as an euphemism for civilian casualties of a military action.-Etymology:...

 (such as on an aircraft). In essence, the hollow point bullet has two interrelated purposes: to increase its size once within the target, thus maximizing tissue damage and blood loss or shock, and by remaining in the target to expend all of its kinetic energy in the target, some of which will be lost if the bullet continues through the target. Jacketed hollow points (JHPs) or plated hollow points are covered in a coating of harder metal to increase bullet strength and to prevent fouling
Fouling
Fouling refers to the accumulation of unwanted material on solid surfaces, most often in an aquatic environment. The fouling material can consist of either living organisms or a non-living substance...

 the barrel with lead stripped from the bullet. The term hollow-cavity bullet is used to describe a hollow point where the hollow is unusually large, sometimes dominating the volume of the bullet, and causes extreme expansion or fragmentation on impact.

Mechanism of action

Expansion

When a hollow-point hunting bullet strikes a soft target, the pressure created in the pit forces the material (usually lead) around the inside edge to expand outwards, increasing the axial diameter of the projectile as it passes through. This process is commonly referred to as mushrooming, because the resulting shape, a widened, rounded nose on top of a cylindrical base, typically resembles a mushroom
Mushroom
A mushroom is the fleshy, spore-bearing fruiting body of a fungus, typically produced above ground on soil or on its food source. The standard for the name "mushroom" is the cultivated white button mushroom, Agaricus bisporus; hence the word "mushroom" is most often applied to those fungi that...

.

The greater frontal surface area of the expanded bullet limits its depth of penetration into the target, and causes more extensive tissue damage along the wound path. Many hollow-point bullets, especially those intended for use at high velocity in centerfire rifles, are jacketed, i.e. a portion of the lead-cored bullet is wrapped in a thin layer of harder metal, such as copper
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...

 or mild steel
Steel
Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...

. This jacket provides additional strength to the bullet, and can help prevent it from leaving deposits of lead inside the bore. In controlled expansion bullets, the jacket and other internal design characteristics help to prevent the bullet from breaking apart; a fragmented bullet will not penetrate as far.

Accuracy

Where target shooting accuracy is the prime consideration, some bullets such as the Sierra "Matchking" incorporate a cavity in the nose section. This has the effect of lightening the bullet's forward section and shifting the center of mass towards the tail of the bullet, to give an improved ballistic coefficient
Ballistic coefficient
In ballistics, the ballistic coefficient of a body is a measure of its ability to overcome air resistance in flight. It is inversely proportional to the negative acceleration—a high number indicates a low negative acceleration. BC is a function of mass, diameter, and drag coefficient...

, greater down-range velocity retention, and greater resistance to deflection
Deflection
Deflection or deflexion may refer to:* Deflection , the displacement of a structural element under load* Deflection , a technique of shooting ahead of a moving target so that the target and projectile will collide...

 by crosswinds. The manufacturing process of hollow-point bullets also produces a flat, uniformly-shaped base on the bullet which increases accuracy by providing a more consistent piston surface for the expanding gases of the cartridge.

Match or target hollow-point bullets are designed for precision target use, and no consideration is given to their expansion or other terminal ballistic performance. The United States military, for example, uses hollow-point bullets in some sniper
Sniper
A sniper is a marksman who shoots targets from concealed positions or distances exceeding the capabilities of regular personnel. Snipers typically have specialized training and distinct high-precision rifles....

 rifles for their exceptional accuracy at long ranges, and believes that the hollow-point does not result in wounds significantly different from full metal jacket
Full metal jacket bullet
A full metal jacket is a bullet consisting of a soft core encased in a shell of harder metal, such as gilding metal, cupronickel or less commonly a steel alloy. This shell can extend around all of the bullet, or often just the front and sides with the rear left as exposed lead...

 ammunition in practice. Some hunters, however, have reported good expansion characteristics and quick, "humane kills" from hollow-point target bullets.

Hollow-point Boat-tail

A hollow-point boat-tail (HPBT) bullet is a match grade bullet design that uses the concept of a teardrop-like shape to give it a lower drag coefficient and make it produce less turbulence in its wake. Only the base of the bullet has a boat tail-like shape — the meplat
Meplat
Meplat, from a French term for a flat surface, is the technical term for the tip or nose of a bullet. The shape of the meplat is important when determining how the bullet will move through the air. If uneven, the bullet will not have an ideal flight characteristic and will most likely not be of the...

 is still pointed. Some hollow-point boat-tail bullets with longer, more aerodynamic profiles are known as very-low-drag (VLD) bullets
Very-low-drag bullet
Very-low-drag bullets are primarily a small arms ballistics development of the 1980s–1990s, driven by shooters' desire for bullets that will give a higher degree of accuracy and kinetic efficiency, especially at extended ranges. To achieve this the projectile must minimize air resistance in flight...

.

Testing

Terminal ballistics
Terminal ballistics
Terminal ballistics, a sub-field of ballistics, is the study of the behavior of a projectile when it hits its target. It is often referred to as stopping power when dealing with human or other living targets. Terminal ballistics is relevant both for small caliber projectiles as well as for large...

 testing of hollow-point bullets is generally performed in ballistic gelatin
Ballistic gelatin
Ballistic Gelatin is a testing medium scientifically correlated to swine muscle tissue , in which the effects of bullet wounds can be simulated. It was developed and improved by Martin Fackler and others in the field of wound ballistics. Ballistic gelatin is a solution of gelatin powder in water...

, or some other medium intended to simulate tissue and cause a hollow-point bullet to expand. Test results are generally given in terms of expanded diameter, penetration depth, and weight retention. Expanded diameter is an indication of the size of the wound cavity, penetration depth shows if vital organs could be reached by the bullet, and weight retention indicates how much of the bullet mass fragmented and separated from the main body of the bullet. How these different factors are interpreted is subject to the intended use of the bullet, and what constitutes "good" or "bad" performance is subject to disagreement.

History

Solid lead bullets, when cast from a soft alloy, will often deform and provide some expansion if they hit the target at a high velocity. This, combined with the limited velocity and penetration attainable with muzzleloading firearms, meant there was little need for extra expansion.

The first hollow-point bullets were marketed in the late 19th Century as Express bullets, and were hollowed out to reduce the bullet's mass and provide higher velocities. In addition to providing increased velocities, the hollow also turned out to provide significant expansion, especially when the bullets were cast in a soft lead
Lead
Lead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...

 alloy
Alloy
An alloy is a mixture or metallic solid solution composed of two or more elements. Complete solid solution alloys give single solid phase microstructure, while partial solutions give two or more phases that may or may not be homogeneous in distribution, depending on thermal history...

. Originally intended for rifles, the popular .32-20, .38-40 and .44-40 calibers could also be fired in revolver
Revolver
A revolver is a repeating firearm that has a cylinder containing multiple chambers and at least one barrel for firing. The first revolver ever made was built by Elisha Collier in 1818. The percussion cap revolver was invented by Samuel Colt in 1836. This weapon became known as the Colt Paterson...

s.

With the advent of smokeless powder
Smokeless powder
Smokeless powder is the name given to a number of propellants used in firearms and artillery which produce negligible smoke when fired, unlike the older gunpowder which they replaced...

, velocities increased, and bullets got smaller, faster, and lighter. These new bullets (especially in rifles) needed to be jacketed to handle the conditions of firing. The new full metal jacket
Full metal jacket bullet
A full metal jacket is a bullet consisting of a soft core encased in a shell of harder metal, such as gilding metal, cupronickel or less commonly a steel alloy. This shell can extend around all of the bullet, or often just the front and sides with the rear left as exposed lead...

 bullets tended to penetrate straight through a target and produce little damage. This led to the development of the soft point bullet
Soft point bullet
A soft-point bullet , also known as a soft-nosed bullet, is a lead expanding bullet with a copper or brass jacket that is left open at the tip, exposing some of the lead inside and is thus an example of a semi-jacketed round...

 and later jacketed hollow-point bullets at the British
British Empire
The British Empire comprised the dominions, colonies, protectorates, mandates and other territories ruled or administered by the United Kingdom. It originated with the overseas colonies and trading posts established by England in the late 16th and early 17th centuries. At its height, it was the...

 arsenal
Arsenal
An arsenal is a place where arms and ammunition are made, maintained and repaired, stored, issued to authorized users, or any combination of those...

 in Dum Dum
Dum Dum
Dum Dum is a city and a municipality in North 24 Parganas district in the state of West Bengal, India. It is a neighbourhood in North-west Kolkata and the location of Netaji Subhash Chandra Bose International Airport, formerly Dum Dum Airport.Dum Dum is a well known place in greater Kolkata...

, near Calcutta
Kolkata
Kolkata , formerly known as Calcutta, is the capital of the Indian state of West Bengal. Located on the east bank of the Hooghly River, it was the commercial capital of East India...

 around 1890. Designs included the .303" Mk III, IV & V
.303 British
.303 British, or 7.7x56mmR, is a .311 inch calibre rifle and machine gun cartridge first developed in Britain as a blackpowder round put into service in December 1888 for the Lee-Metford rifle, later adapted to use smokeless powders...

 and the .455" Mk III "Manstopper"
.455 Webley
.455 Webley is a British handgun cartridge, most commonly used in the Webley top break revolvers Marks I through VI.The .455 cartridge was a service revolver cartridge, featuring a rimmed cartridge firing a .45 bullet at the relatively low velocity of 650 ft/s...

 cartridges. Although such bullet designs were quickly outlawed for use in warfare (they were said by the German military to have breached the terms of the Hague Convention
Hague Conventions (1899 and 1907)
The Hague Conventions were two international treaties negotiated at international peace conferences at The Hague in the Netherlands: The First Hague Conference in 1899 and the Second Hague Conference in 1907...

), they steadily gained ground among hunters due to the ability to control the expansion of the new high velocity cartridges. In modern ammunition, the use of hollow points is primarily limited to handgun ammunition, which tends to operate at much lower velocities than rifle ammunition (on the order of 1000 foot per second versus over 2,000 feet per second). At rifle velocities, a hollow point is not needed for reliable expansion and most rifle ammunition makes use of tapered jacket designs to achieve the mushrooming effect. At the lower handgun velocities, hollow point designs are generally the only design which will expand reliably.
Modern hollowpoint bullet designs use many different methods to provide controlled expansion, including:
  • Jackets that are thinner near the front than the rear to allow easy expansion at the beginning, then a reduced expansion rate
  • Partitions in the middle of the bullet core to stop expansion at a given point
  • Bonding the lead core to the copper jacket to prevent separation and fragmentation
  • Fluted or otherwise weakened jackets to encourage expansion or fragmentation
  • Posts in the hollow cavity to cause hydraulic expansion of the bullet in tissue. While very effective in lightly clothed targets, these bullet types tend to plug up with heavy clothing materials that results in the bullet not expanding.
  • Solid copper hollow points, which are far stronger than jacketed lead, and provide controlled, uniform expansion even at high velocities
  • Plastic inserts in the hollow, which provide the same profile as a full metal jacketed round (such as the Hornady
    Hornady
    Hornady Manufacturing Company is an American manufacturer of ammunition and handloading components, based in Grand Island, Nebraska.The company was founded by Joyce Hornady in 1949 and is currently run by his son Steve Hornady who took over after his father's death in a plane crash in 1981.Hornady...

     V-Max bullet). The plastic insert initiates the expansion of the bullet by being forced into the hollow cavity upon impact.
  • Plastic inserts in the hollow to provide the same profile for feeding in semiautomatic and automatic weapons as a full metal jacketed round but that separate on firing while in flight or in the barrel (such as the German Geco "Action Safety" 9 mm round)

Legality

The Hague Convention
Hague Conventions (1899 and 1907)
The Hague Conventions were two international treaties negotiated at international peace conferences at The Hague in the Netherlands: The First Hague Conference in 1899 and the Second Hague Conference in 1907...

 of 1899, Declaration III, prohibits the use in warfare of bullets that easily expand or flatten in the body.
This is often incorrectly believed to be prohibited in the Geneva Conventions
Geneva Conventions
The Geneva Conventions comprise four treaties, and three additional protocols, that establish the standards of international law for the humanitarian treatment of the victims of war...

, but it significantly predates those conventions, and is in fact a continuance of the St. Petersburg Declaration of 1868, which banned exploding projectiles of less than 400 grams, as well as weapons designed to aggravate injured soldiers or make their death inevitable. NATO members do not use small arms ammunition that is prohibited by the Hague Convention.

Despite the ban on military use, hollow-point bullets are one of the most common types of civilian and police
Police
The police is a personification of the state designated to put in practice the enforced law, protect property and reduce civil disorder in civilian matters. Their powers include the legitimized use of force...

 ammunition
Ammunition
Ammunition is a generic term derived from the French language la munition which embraced all material used for war , but which in time came to refer specifically to gunpowder and artillery. The collective term for all types of ammunition is munitions...

, due largely to the reduced risk of bystanders being hit by over-penetrating or ricocheted bullets, and the increased speed of incapacitation. In many jurisdiction
Jurisdiction
Jurisdiction is the practical authority granted to a formally constituted legal body or to a political leader to deal with and make pronouncements on legal matters and, by implication, to administer justice within a defined area of responsibility...

s, even ones such as the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

, where expanding ammunition is generally prohibited, it is illegal to hunt
Hunting
Hunting is the practice of pursuing any living thing, usually wildlife, for food, recreation, or trade. In present-day use, the term refers to lawful hunting, as distinguished from poaching, which is the killing, trapping or capture of the hunted species contrary to applicable law...

 certain types of game
Game (food)
Game is any animal hunted for food or not normally domesticated. Game animals are also hunted for sport.The type and range of animals hunted for food varies in different parts of the world. This will be influenced by climate, animal diversity, local taste and locally accepted view about what can or...

 with ammunition that does not expand. Some target ranges forbid full metal jacket
Full metal jacket bullet
A full metal jacket is a bullet consisting of a soft core encased in a shell of harder metal, such as gilding metal, cupronickel or less commonly a steel alloy. This shell can extend around all of the bullet, or often just the front and sides with the rear left as exposed lead...

 ammunition, due to its greater tendency to damage metal targets and backstops.

United States of America

The state of New Jersey
New Jersey
New Jersey is a state in the Northeastern and Middle Atlantic regions of the United States. , its population was 8,791,894. It is bordered on the north and east by the state of New York, on the southeast and south by the Atlantic Ocean, on the west by Pennsylvania and on the southwest by Delaware...

 prohibits the possession and use of hollow-point ammunition by private citizens, specifically in firearms carried outside the home, but with many exceptions. see: gun laws in New Jersey

United Kingdom

All expanding ammunition, including hollow point bullets, falls under Section 5 (prohibited weapons) of the Firearms Act 1968
Firearms Act 1968
The Firearms Act of 1968 is a UK Act of Parliament controlling use and possession of firearms....

 and so is illegal to possess or transfer without the written permission of the Home Secretary. The law is in conflict with 'Schedule 2' of 'The Deer Act 1991', prohibiting the use of any ammunition other than soft-nosed or hollow-point bullets for the killing of deer. Because of this conflict, Section 5A(4) allows the police licensing authority to add a condition to a firearm certificate for possession of expanding ammunition for:
  1. the lawful shooting of deer
    Deer
    Deer are the ruminant mammals forming the family Cervidae. Species in the Cervidae family include white-tailed deer, elk, moose, red deer, reindeer, fallow deer, roe deer and chital. Male deer of all species and female reindeer grow and shed new antlers each year...

  2. the shooting of vermin
    Vermin
    Vermin is a term applied to various animal species regarded by some as pests or nuisances and especially to those associated with the carrying of disease. Since the term is defined in relation to human activities, which species are included will vary from area to area and even person to person...

     or, in the case of carrying on activities in connection with the management of any estate, other wildlife
    Wildlife
    Wildlife includes all non-domesticated plants, animals and other organisms. Domesticating wild plant and animal species for human benefit has occurred many times all over the planet, and has a major impact on the environment, both positive and negative....

  3. the humane killing of animals
  4. the shooting of animals for the protection of other animals or humans

Winchester Black Talon controversy

In early 1992 Winchester introduced the "Black Talon
Black Talon
Black Talon is a type of ammunition that was introduced by Winchester Ammunition in 1991 primarily for law enforcement and self-defense. This hollow-point ammunition became known for its bullet's unique construction and sharp petal shape after expansion following impact with tissue or other wet media...

", a newly designed hollow-point handgun bullet which used a specially designed, reverse tapered jacket. The jacket was cut at the hollow to intentionally weaken it, and these cuts allowed the jacket to open into six petals upon impact. The thick jacket material kept the tips of the jacket from bending as easily as a normal thickness jacket. The slits that weakened the jacket left triangular shapes in the tip of the jacket, and these triangular sections of jacket would end up pointing out after expansion, leading to the "Talon" name. The bullets were coated with a black colored, paint-like lubricant called "Lubalox," and loaded into nickel-plated brass cases, which made them visually stand out from other ammunition. While actual performance of the Black Talon rounds was not significantly better than any other comparable high performance hollow-point ammunition, the reverse taper jacket did provide reliable expansion under a wide range of conditions, and many police departments adopted the round.

Winchester's "Black Talon" product name was eventually used against them. After a high profile shooting at 101 California Street
101 California Street shootings
101 California Street Shootings is the name given to a mass shooting that took place July 1, 1993 in San Francisco, California, claiming the lives of nine people including the shooter. The killings sparked a number of legal and legislative actions that were precursors to the Violent Crime Control...

, San Francisco in 1993, media response against Winchester was swift. "This bullet kills you better", says one report; "its six razorlike claws unfold on impact, expanding to nearly three times the bullet's diameter".
A concern was raised by the American College of Emergency Physicians
American College of Emergency Physicians
The American College of Emergency Physicians is the first and largest professional organization of emergency medicine physicians in the United States. It was founded in 1968 and is now headquartered in Irving, Texas. As of 2009 ACEP has over 28,000 physician members.The college exists to support...

 that the sharp edges of the jacket could penetrate surgical gloves, increasing the risk of blood-borne infections being transmitted to medical personnel treating the gunshot wound. While possible, there are no recorded cases of such an infection occurring in relation to the Black Talon bullets.

Winchester responded to the media criticism of the Black Talon line by removing it from the civilian market and only selling it to law enforcement distributors. Winchester has since discontinued the sale of the Black Talon entirely, although Winchester does market very similar ammunition, the Ranger T-Series to law enforcement and the Supreme Elite Bonded PDX1 to civilians.

Terminology

The hollow point and soft-nosed bullets are both sometimes also referred to as dum-dum
Dum-dum
An expanding bullet is a bullet designed to expand on impact, increasing in diameter to limit penetration and/or produce a larger diameter wound. They are informally known as a Dum-dum or dumdum bullets...

s, so named after the British arsenal at Dum Dum, in present north Kolkata
Kolkata
Kolkata , formerly known as Calcutta, is the capital of the Indian state of West Bengal. Located on the east bank of the Hooghly River, it was the commercial capital of East India...

, India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

, where it is said jacketed, expanding bullets were first developed. This term is rare among shooters, but can still be found in use, usually in the news media and sensational popular fiction.
Recreational shooters sometimes refer to hollow points as "JHPs", from the common manufacturer's abbreviation for "Jacketed Hollow Point".

To be most correct, the term "Dum Dum Bullet" refers only to Soft-point bullets, not to hollow points, though it is very common for it to be mistakenly used this way.

See also

  • Ballistic tip bullet
    Ballistic tip bullet
    Plastic tipped bullets are a type of bullet meant to confer the advantages of both spitzer point bullet and hollow point bullets. They consist of a fairly normal hollow-point bullet with the frontal cavity filled in by hard plastic, which is molded into a streamlined shape mimicking the shape of a...

  • Ammunition
    Ammunition
    Ammunition is a generic term derived from the French language la munition which embraced all material used for war , but which in time came to refer specifically to gunpowder and artillery. The collective term for all types of ammunition is munitions...

  • Full Metal Jacket
    Full metal jacket bullet
    A full metal jacket is a bullet consisting of a soft core encased in a shell of harder metal, such as gilding metal, cupronickel or less commonly a steel alloy. This shell can extend around all of the bullet, or often just the front and sides with the rear left as exposed lead...


Further reading


External links

  • High speed video clips of several Barnes expanding bullets on impact. The 180 grain .308 bullet shows an ideal mushroom shape in the ballistic gelatin
    Ballistic gelatin
    Ballistic Gelatin is a testing medium scientifically correlated to swine muscle tissue , in which the effects of bullet wounds can be simulated. It was developed and improved by Martin Fackler and others in the field of wound ballistics. Ballistic gelatin is a solution of gelatin powder in water...

    , and clearly shows the ripples in the temporary cavity formed by the spinning bullet.
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