Wildcat cartridge
Encyclopedia
A wildcat cartridge, or wildcat, is a custom cartridge for which 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...

 and firearms are not mass produced. These cartridges are often created in order to optimize a certain performance characteristic (such as the power, size or efficiency) of an existing commercial cartridge.

Developing and using wildcat cartridges does not generally serve a purpose in military or law enforcement; it is more a hobby for serious shooting, hunting
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...

, gunsmithing and handloading
Handloading
Handloading or reloading is the process of loading firearm cartridges or shotgun shells by assembling the individual components , rather than purchasing completely assembled, factory-loaded cartridges...

 enthusiasts, particularly in the United States. There are potentially endless amounts of different kinds of wildcat cartridges: one source of gunsmithing equipment has a library of over 6,000 different wildcat cartridges for which they produce equipment such as chamber reamer
Chamber reamer
A chamber reamer is a specific type of fluted reamer used by gunsmiths and firearms manufacturers to cut the chamber of a handgun, rifle, or shotgun. The chamber reamer is inserted into the bore of a barrel and held stationary while the barrel is turned around it...

s.

Development of a wildcat

Often, wildcats are commercially sold rounds that have been modified in some way to alter the cartridge's performance. Barrels for the caliber are originally manufactured by gunsmith
Gunsmith
A gunsmith is a person who repairs, modifies, designs, or builds firearms. This occupation is different from an armorer. The armorer primarily maintains weapons and limited repairs involving parts replacement and possibly work involving accurization...

s specializing in barrel making. Generally the same makers also offer reloading dies, tools to custom-load bullets into cases. Because changing the barrel
Gun barrel
A gun barrel is the tube, usually metal, through which a controlled explosion or rapid expansion of gases are released in order to propel a projectile out of the end at a high velocity....

 of a gun to accommodate custom cartridges requires precision equipment, most wildcats are developed by or in association with custom barrel makers. Ammunition is handloaded
Handloading
Handloading or reloading is the process of loading firearm cartridges or shotgun shells by assembling the individual components , rather than purchasing completely assembled, factory-loaded cartridges...

, using modified parent cases and the gunsmith-provided wildcat dies. Generally the supplier of the barrel or dies will also provide the buyer with basic reloading data, giving a variety of powders, charge weights, and bullet weights that can be used for developing loads. Handloaders use the data to develop a load by starting with minimum loads and carefully working up.

Wildcat cases and cartridges can be found for sale, but only from small makers. Larger manufacturers usually don't produce wildcats because there is such a limited market for them and because there are no established CIP
CIP
-Business:* Carriage and Insurance Paid to, an Incoterm* Construction in Progress, in accountancy, a balance sheet assets item used for assets being constructed, e.g...

 (Commission Internationale Permanente Pour L'Epreuve Des Armes A Feu Portatives - Permanent International Commission) or SAAMI
Sporting Arms and Ammunition Manufacturers' Institute
The Sporting Arms and Ammunition Manufacturers' Institute is an association of American firearms and ammunition manufacturers...

 standards, which causes liability concerns.

Wildcat goals and methods

Wildcat cartridges are developed for many reasons. Generally, the goal is to optimize some characteristic of a commercial cartridge in a given context. Higher velocities, greater energy, better efficiency, greater consistency (which yields greater accuracy) and complying to a minimal permitted calibre or bullet weight for the legal hunting of certain species of game in a particular jurisdiction are the top reasons. The sport of metallic silhouette
Metallic silhouette
Metallic silhouette shooting is a group of target shooting disciplines that involves shooting at metal cutouts representing game animals at varying distances. Metallic silhouette shooting can be done with airguns, black powder firearms, modern handguns, or modern rifles...

 shooting, has given rise to a great number of wildcats, as several rifle rounds are adapted to fire from a handgun
Handgun
A handgun is a firearm designed to be held and operated by one hand. This characteristic differentiates handguns as a general class of firearms from long guns such as rifles and shotguns ....

. In using autopistols for hunting or competitive shooting, improved feeding of softnose or hollowpoint bullets is also an issue; the bottleneck
Bottleneck
A bottleneck is a phenomenon where the performance or capacity of an entire system is limited by a single or limited number of components or resources. The term bottleneck is taken from the 'assets are water' metaphor. As water is poured out of a bottle, the rate of outflow is limited by the width...

ed .45/38, for instance, was created because the straight-cased .45 ACP
.45 ACP
The .45 ACP , also known as the .45 Auto by C.I.P., is a cartridge designed by John Browning in 1904, for use in his prototype Colt semi-automatic .45 pistol and eventually the M1911 pistol adopted by the United States Army in 1911.-Design and history:The U.S...

 had trouble feeding hollowpoints.

Wildcat cartridges are generally developed because:
  • Higher velocities can be obtained by increasing the case capacity, or reducing the caliber.
  • Greater energy can be attained by increasing the caliber or the case capacity.
  • Better efficiency can be achieved by increasing the shoulder angle, shortening the case, and reducing case taper (see internal ballistics
    Internal ballistics
    Internal ballistics, a subfield of ballistics, is the study of a projectile's behavior from the time its propellant's igniter is initiated until it exits the gun barrel...

    ).
  • Greater consistency can be achieved by tuning the case capacity to a certain bullet diameter, weight, and velocity that give consistent results.
  • Feeding problems can be fixed.


Some methods used to develop a wildcat are:
  • Cold forming. The parent case is well lubricated and forced carefully into the reloading die for the wildcat caliber. This will swage
    Swage
    Swaging is a forging process in which the dimensions of an item are altered using a die or dies, into which the item is forced. Swaging is usually a cold working process; however, it is sometimes done as a hot working process....

     the case into the new shape. This type of operation is used for reducing case dimensions, such as reducing the neck diameter or pushing the shoulder back, or changing the neck diameter.
  • Fire forming
    Fire forming
    The term fire forming in firearms refers to the process of reshaping a metallic cartridge case to fit a new chamber by firing it within that chamber...

    . This consists of taking the parent case, or a partially cold formed case, loading it with a light bullet and light load of powder, and firing it in the firearm it will be used in. Another technique uses a charge of fast burning powder topped with a case full of Cream of Wheat
    Cream of Wheat
    Cream of Wheat is a porridge-type breakfast food invented in 1893 by wheat millers in Grand Forks, North Dakota. The cereal is currently manufactured and sold by B&G Foods. Until 2007, it was the Nabisco brand made by Kraft Foods. It is similar in texture to grits, but made with farina instead...

     and a wad, to form a special blank cartridge
    Blank (cartridge)
    A blank is a type of cartridge for a firearm that contains gunpowder but no bullet or shot. When fired, the blank makes a flash and an explosive sound . Blanks are often used for simulation , training, and for signaling...

     that will expand the case. This technique is used for increasing case dimensions, such as pushing the neck forward, increasing the neck angle, or straightening the case walls.
  • Trimming to length. Generally, after either a cold forming or a fire forming operation, the mouth of the case will be longer than ideal, and the case will be trimmed back to the "trim to" length. Trimming is a normal reloading operation, as high pressure cartridges will flow each time they are fired, and periodically need trimming to remove the brass that flows to the mouth.
  • Changing the diameter of the bullet. Called "necking up" or "necking down", this is the most common way of making a wildcat. The new caliber allows a much different range of bullet weights, and can greatly increase the velocity or the power or the resistance to wind drift as compared to the parent cartridge.
  • Necking back. This is a cold forming operation in which the neck is pushed back to reduce case capacity. This is often done when developing rounds for shorter barrels, such as turning a rifle
    Rifle
    A rifle is a firearm designed to be fired from the shoulder, with a barrel that has a helical groove or pattern of grooves cut into the barrel walls. The raised areas of the rifling are called "lands," which make contact with the projectile , imparting spin around an axis corresponding to the...

     cartridge into a handgun
    Handgun
    A handgun is a firearm designed to be held and operated by one hand. This characteristic differentiates handguns as a general class of firearms from long guns such as rifles and shotguns ....

     cartridge.
  • Blowing out. This is a fire forming operation that moves the shoulder forward to increase case capacity.
  • Changing the shoulder angle. By making the shoulder closer to square, the resulting space is closer to the ideal spherical shape, resulting in a more efficient burn. If the shoulder is also to be moved back, this is a cold forming operation; if the shoulder is to stay or be moved forward, it is a hot forming operation.
  • Reducing the case taper. This hot forming operation makes the cartridge more cylindrical, giving similar results to a shoulder angle change.
  • Changing the rim. While this is a wildcatting operation, it is generally only done by commercial operations, due to the precision turning
    Turning
    Turning is the process whereby a single point cutting tool is parallel to the surface. It can be done manually, in a traditional form of lathe, which frequently requires continuous supervision by the operator, or by using a computer controlled and automated lathe which does not. This type of...

     needed. Generally this is a conversion from rimmed to rimless cartridge, or from rimless to rebated, and is done to allow a larger parent case than the firearm action
    Firearm action
    In firearms terminology, an action is the physical mechanism that manipulates cartridges and/or seals the breech. The term is also used to describe the method in which cartridges are loaded, locked, and extracted from the mechanism. Actions are generally categorized by the type of mechanism used...

     was designed for. The opposite operation, adding a rim to a case, is also generally only done by major manufacturers; examples are the .45 Auto Rim, a rimmed .45 ACP allowing ejection in .45 revolvers without the use of moon clips, and the .307 Winchester
    .307 Winchester
    The 307 Winchester cartridge was introduced by Winchester in 1982 to meet the demand of .300 Savage performance in a lever-action rifle equipped with a tubular magazine...

    , a rimmed .308 Winchester
    .308 Winchester
    The .308 Winchester is a rifle cartridge and is the commercial cartridge upon which the military 7.62x51mm NATO centerfire cartridge is based. The .308 Winchester was introduced in 1952, two years prior to the NATO adoption of the 7.62x51mm NATO T65...

    , developed for use in lever-action rifles. A handloader can add a rim, by swaging a ring of metal onto a rimless case, then turning it down, but this is very labor intensive process and requires a special swaging die and precision metalworking lathe
    Lathe
    A lathe is a machine tool which rotates the workpiece on its axis to perform various operations such as cutting, sanding, knurling, drilling, or deformation with tools that are applied to the workpiece to create an object which has symmetry about an axis of rotation.Lathes are used in woodturning,...

    . It is far easier for most handloaders to simply start with a rimmed case, either of the desired diameter or reamed out as desired.
  • Increasing the case length. This process (which allows the cartridge to contain more propellant and thus increases potential energy of the bullet) was used to make the powerful .357 Magnum
    .357 Magnum
    The .357 S&W Magnum , or simply .357 Magnum, is a revolver cartridge created by Elmer Keith, Phillip B. Sharpe, Colonel D. B. Wesson of firearms manufacturer Smith & Wesson, and Winchester. It is based upon Smith & Wesson's earlier .38 Special cartridge. The .357 Magnum cartridge was introduced in...

     cartridge from the much weaker .38 Special
    .38 Special
    The .38 Smith & Wesson Special is a rimmed, centerfire cartridge designed by Smith & Wesson. It is most commonly used in revolvers, although some semi-automatic pistols and carbines also use this round...

    : A .357 magnum bullet has more than 3 times more energy
    Energy
    In physics, energy is an indirectly observed quantity. It is often understood as the ability a physical system has to do work on other physical systems...

     than a .38 special bullet of the same weight. Increasing the length of a bullet's case usually involves getting rid of the old case and making a completely new one from scratch, which all but limits the feasibility of this kind of modification to commercial manufactures. It is possible to draw an existing case into a slightly longer form, thinning and stretching the existing case, but this is an operation requiring special equipment and expertise. It is far easier and more common to reduce, not extend the length of a case.

Example wildcat cartridges

In terms of sheer numbers of varieties, there are more wildcat cartridges than there are production cartridges. Most wildcats are custom made, and therefore are not generally well-known. Some wildcat cartridges, however, are produced commercially in small quantities by small manufacturers. This is a list of some representative wildcats.
  • .30 Herrett. Based on the .30-30 Winchester
    .30-30 Winchester
    The .30-30 Winchester/.30 Winchester Center Fire/7.62×51mmR cartridge was first marketed in early 1895 for the Winchester Model 1894 lever-action rifle. The .30-30 , as it is most commonly known, was the USA's first small-bore, sporting rifle cartridge designed for smokeless powder. The .30-30 is...

    , necked back and with a sharper shoulder angle. Developed for use in pistols with barrels as short as 10 inches (25 cm), it develops the same power as a .30-30 with greater efficiency and less muzzle blast.
  • .357 Herrett. Like the earlier .30 Herrett, this cartridge is based on the .30-30 Winchester, shortened and necked up to .357 (9 mm). Designed for use in short barrels, the resulting cartridge is more efficient and more powerful than the .30-30. Often considered one of the best medium game hunting calibers available in the 10" (25 cm) barrelled Thompson Center Arms
    Thompson Center Arms
    Thompson/Center Arms Company is an American firearms company based in Rochester, New Hampshire. The company is best known for its line of interchangeable barrel single-shot pistols and rifles. Thompson Center manufactures muzzleloading rifles and is credited with creating the resurgence of their...

     Contender pistol.
  • .10 Eichelberger Long Rifle. This is one of a smaller number of wildcats based on rimfire cartridges. It is made by disassembling a .22 Long Rifle
    .22 Long Rifle
    The .22 Long Rifle rimfire cartridge is a long established variety of ammunition, and in terms of units sold is still by far the most common in the world today. The cartridge is often referred to simply as .22 LR and various rifles, pistols, revolvers, and even some smoothbore shotguns have...

     cartridge, and re-using the case. The .10 caliber (2.5 mm) is the smallest rifled barrel made. The tiny .10 caliber bullets produce almost no recoil and travel at very high velocities. While it can be used on small game at short ranges, this cartridge is more of a curiosity than a practical hunting or target round.
  • 5.7 MMJ, or 5.7mm Spitfire. A .30 Carbine
    .30 Carbine
    The .30 Carbine is the cartridge used in the M1 Carbine introduced in the 1940s. It is an intermediate round designed to be fired from the M1 carbine's 18-inch barrel.-History:...

     case necked down to .223 caliber (5.56 mm), this cartridge was developed to convert military surplus M1 Carbine
    M1 Carbine
    The M1 carbine is a lightweight, easy to use semi-automatic carbine that became a standard firearm for the U.S. military during World War II, the Korean War and the Vietnam War, and was produced in several variants. It was widely used by U.S...

    s into short range varmint guns.
  • 6 mm PPC
    6 mm PPC
    The 6 mm PPC , or 6 PPC as it is more often called, is a centerfire rifle cartridge used almost exclusively for benchrest shooting. At distances out to 300 yards, it is one of the most accurate cartridges available...

    . Based on the .220 Russian, which is in turn based on the 7.62 x 39 mm assault rifle
    Assault rifle
    An assault rifle is a selective fire rifle that uses an intermediate cartridge and a detachable magazine. Assault rifles are the standard infantry weapons in most modern armies...

     cartridge. The 6 mm PPC was developed in 1975 specifically for benchrest shooting
    Benchrest shooting
    Benchrest shooting is a sport in which very accurate and precise rifles are shot at paper targets from a rest or bench from a sitting position. Benchrest shooters are notoriously detail-oriented and constantly trying to further the accuracy potential of the rifle through experimentation. Nearly...

    . While it is anything but common anywhere else, the 6 mm PPC unseated the .222 Remington from its 20 year spot as the best benchrest cartridge available. Chambered only in single-shot
    Single-shot
    Single-shot firearms are firearms that hold only a single round of ammunition, and must be reloaded after each shot. The history of firearms began with single-shot designs, and many centuries passed before multi-shot designs became commonplace...

     rifles due to its short, fat case and sharp shoulder angle, the 6 mm PPC is still going strong in benchrest after 30 years.
  • .22 Eargesplitten Loudenboomer
    .22 Eargesplitten Loudenboomer
    .22 Eargesplitten Loudenboomer is a cartridge for a rifle.It was invented in the 1960s by P.O. Ackley to set a world record for firing bullets at over 5000 fps . The round failed to reach the desired velocity, but reached 4600 fps with a 50 grain bullet and 105 grains of H570 powder. It is based...

    . This humorously named cartridge was developed by P. O. Ackley specifically to exceed 5000 ft/s (1,524 m/s) muzzle velocity. Based on a .378 Weatherby Magnum
    .378 Weatherby Magnum
    The .378 Weatherby Magnum was designed by Roy Weatherby in 1953. It was an original belted magnum design with no parent case, inspired by the .416 Rigby and headspacing of the belted .375 H&H Magnum. The 215 magnum rifle primer was developed by Federal specifically for this round. The cartridge can...

     case, the case is impractically overpowered for the bore diameter, and so the cartridge remains a curiosity.
  • 7 mm TCU (also known as 7TCU). Based on the .223 Remington
    .223 Remington
    The .223 Remington is a sporting cartridge with almost the same external dimensions as the 5.56×45mm NATO military cartridge. The name is commonly pronounced either two-two-three or two-twenty-three. It is loaded with a diameter, jacketed bullet, with weights ranging from , though the most common...

     case, the 7 mm TCU is popular in single-shot handguns such as the Thompson Center Arms' Contender and G2 Contender. It is but one of a family of wildcat TCU cartridges
    Thompson/Center Ugalde
    The Thompson/Center Ugalde, or TCU family of wildcat cartridges was developed by Wes Ugalde of Fallon, Nevada, by necking up .223 Remington brass to accept larger bullets...

    .

Wildcat cartridges in Australia

In Australia, wildcat cartridges were relatively common. Most are made primarily for hunting species such as 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...

, kangaroo
Kangaroo
A kangaroo is a marsupial from the family Macropodidae . In common use the term is used to describe the largest species from this family, especially those of the genus Macropus, Red Kangaroo, Antilopine Kangaroo, Eastern Grey Kangaroo and Western Grey Kangaroo. Kangaroos are endemic to the country...

, are generally based on the .303 British
.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...

 because of the post war popularity of that round and of the cheap surplus Australian Lee-Enfield MkIII military rifles avaialable. Many of these surplus rifles were rebarreled to 257 caliber, known as the 303-25. One of the unique features is that these cartridges relied less on handloading - and instead were offered as proprietary cartridges from gunsmiths.

Since having an existing barrel rebored and rechambered was (at that time) less expensive than fitting a new barrel, a 303-25 rifle with a shotout barrel could be economically converted to .277 caliber, known as the 303-270.

The .222 Remington
.222 Remington
The .222 Remington aka the Triple Deuce/Triple Two/Treble Two is a centerfire rifle cartridge introduced in 1950, and was the first commercial rimless .22 cartridge made in the United States...

 - a .222 rimmed in a Martini was also commonly found. As too were the "Tini-Mite" and "Mini-Mite" cartridges, .17 caliber rimfire cartridges based on the .22 Long Rifle case.

Commercially accepted wildcats

Some cartridges started out as custom-made (non-commercially developed) wildcats, and gained wide enough acceptance or popularity to become commercial cartridges. Generally, cartridges become popular commercially after a commercial firearms maker begins offering a weapon chambered in the cartridge. Once popular enough, funding is generated for SAAMI
Sporting Arms and Ammunition Manufacturers' Institute
The Sporting Arms and Ammunition Manufacturers' Institute is an association of American firearms and ammunition manufacturers...

 standards development. After SAAMI
Sporting Arms and Ammunition Manufacturers' Institute
The Sporting Arms and Ammunition Manufacturers' Institute is an association of American firearms and ammunition manufacturers...

 standards are in place, any firearms or ammunition maker can be sure that any products manufactured to the SAAMI
Sporting Arms and Ammunition Manufacturers' Institute
The Sporting Arms and Ammunition Manufacturers' Institute is an association of American firearms and ammunition manufacturers...

 standards can be safely used.

Some examples of custom cartridges that became commercially accepted are:
  • .22-250. Based on a .250 Savage case, the .22-250 is still one of the fastest shooting .22 caliber (5.56 mm) cartridges available. First offered in a factory firearm by Browning in 1963 (the first factory gun chambered for a wildcat), the .22-250 was later adopted by Remington as the .22-250 Remington.
  • .22 Cheetah
    .22 Cheetah
    The .22 CHeetah is a .22 wildcat cartridge developed in the 1970s or 1980s by Jim Carmichel and Fred Huntington....

    . A .308 BR (Bench Rest) case necked down to .22 caliber, the .22 Cheetah provides a flat trajectory with a .22 caliber bullet that has a relatively high speed of 4,000 ft/s. Hard on barrels, it provides a very effective 300 yard varmint round.
  • .303/25
    .303/25
    The .303/25, sometimes known as the .25/303 is a wildcat centrefire rifle cartridge, based on the .303 British, necked down to fire a .257 projectile, originating in Australia in the 1940s as a cartridge for sporterised rifles, particularly on the Lee Enfield action, similar versions also appeared...

    . A .303 British
    .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...

     cartridge necked down to fire a .25 calibre projectile, developed in Australia during the 1940s as a Kangaroo
    Kangaroo
    A kangaroo is a marsupial from the family Macropodidae . In common use the term is used to describe the largest species from this family, especially those of the genus Macropus, Red Kangaroo, Antilopine Kangaroo, Eastern Grey Kangaroo and Western Grey Kangaroo. Kangaroos are endemic to the country...

     culling
    Culling
    Culling is the process of removing animals from a group based on specific criteria. This is done either to reinforce certain desirable characteristics or to remove certain undesirable characteristics from the group...

     and pest control round. Popularised in the late 1940s and 1950s in New South Wales
    New South Wales
    New South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...

    , owing to restrictions in that state on ownership of .303 British calibre firearm and the difficulties of obtaining commercial hunting arms and ammunition from overseas. Now largely obsolete, but there are still large numbers of converted Lee-Enfield
    Lee-Enfield
    The Lee-Enfield bolt-action, magazine-fed, repeating rifle was the main firearm used by the military forces of the British Empire and Commonwealth during the first half of the 20th century...

     rifles chambered for this round in Australia.
  • 6.8 mm SPC. This cartridge was developed by American military special operations soldiers in search of a more lethal round than the 5.56 x 45 mm NATO
    5.56 x 45 mm NATO
    5.56×45mm NATO is a rifle cartridge developed in the United States and originally chambered in the M16 rifle. Under STANAG 4172, it is a standard cartridge for NATO forces as well as many non-NATO countries. It is derived from, but not identical to, the .223 Remington cartridge...

    . It is based on the .30 Remington cartridge necked down to .270 caliber, and sized to fit in the M16 rifle
    M16 rifle
    The M16 is the United States military designation for the AR-15 rifle adapted for both semi-automatic and full-automatic fire. Colt purchased the rights to the AR-15 from ArmaLite, and currently uses that designation only for semi-automatic versions of the rifle. The M16 fires the 5.56×45mm NATO...

    . The 6.8 SPC is currently deemed unlikely for official military adoption, but is fielded by special operations troops in Afghanistan
    War in Afghanistan (2001–present)
    The War in Afghanistan began on October 7, 2001, as the armed forces of the United States of America, the United Kingdom, Australia, and the Afghan United Front launched Operation Enduring Freedom...

     and Iraq and is gaining popularity as a commercial round.
  • 7 mm-08
    7 mm-08 Remington
    The 7mm-08 Remington is a rifle cartridge that is almost a direct copy of a wildcat cartridge developed around 1958 known as the 7mm/308. As these names would suggest, it is the .308 Winchester case necked down to accept 7 mm bullets with a small increase in case length...

    . A .308 Winchester
    .308 Winchester
    The .308 Winchester is a rifle cartridge and is the commercial cartridge upon which the military 7.62x51mm NATO centerfire cartridge is based. The .308 Winchester was introduced in 1952, two years prior to the NATO adoption of the 7.62x51mm NATO T65...

     necked down to 7 mm (.284 caliber), the 7 mm-08 provides a flatter trajectory with lighter, more aerodynamic 7 mm bullets. It provides nearly the performance of a 7 mm Magnum, but can use a shorter rifle action and does not need a belted case.
  • 7-30 Waters
    7-30 Waters
    The 7-30 Waters cartridge is a wildcat cartridge developed by author Ken Waters in 1976 to give better performance to lever action rifle shooters than the parent .30-30 Winchester cartridge, by providing a higher velocity and flatter trajectory with a smaller, lighter bullet...

    . Designed to improve the performance of lever-action rifle designs dating back to the 1890s, the 7-30 Waters is a .30-30 Winchester
    .30-30 Winchester
    The .30-30 Winchester/.30 Winchester Center Fire/7.62×51mmR cartridge was first marketed in early 1895 for the Winchester Model 1894 lever-action rifle. The .30-30 , as it is most commonly known, was the USA's first small-bore, sporting rifle cartridge designed for smokeless powder. The .30-30 is...

     necked down to 7 mm (.284 caliber). Even with the lower chamber pressures allowed by the lever-action rifle and the flat tipped bullets necessitated by the tubular magazines, the 7-30 Waters offers a significant gain in velocity and sectional density with little loss in bullet weight. This cartridge has also developed a following among handgun hunters using single-shots such as the T/C
    Thompson Center Arms
    Thompson/Center Arms Company is an American firearms company based in Rochester, New Hampshire. The company is best known for its line of interchangeable barrel single-shot pistols and rifles. Thompson Center manufactures muzzleloading rifles and is credited with creating the resurgence of their...

     Contender or G2, which can take advantage of spitzer (pointed) bullets that are unsafe in tubular magazines. It is very efficient on small to medium sized game including whitetails
    White-tailed Deer
    The white-tailed deer , also known as the Virginia deer or simply as the whitetail, is a medium-sized deer native to the United States , Canada, Mexico, Central America, and South America as far south as Peru...

     and mule deer
    Mule Deer
    The mule deer is a deer indigenous to western North America. The Mule Deer gets its name from its large mule-like ears. There are believed to be several subspecies, including the black-tailed deer...

    .
  • .454 Casull
    .454 Casull
    The .454 Casull is a firearm cartridge, developed in 1957 by Dick Casull and Jack Fulmer. It was first announced in November 1959 by Guns & Ammo magazine. The basic design was a lengthened and structurally improved .45 Colt case...

    . This magnum revolver cartridge, a lengthened .45 Colt
    .45 Colt
    The .45 Colt cartridge is a handgun cartridge dating to 1872. It began as a black powder revolver round developed for the Colt Single Action Army revolver, but is offered as a magnum level handgun hunting round in modern usage. This cartridge was adopted by the U.S. Army in 1873 and served as the...

    , was developed by Dick Casull and Jack Fulmer in 1957 as a high-powered big game hunting round. For many years, the small Wyoming manufacturer Freedom Arms was the only substantial maker of guns for the cartridge. In the mid-1990s, two major manufacturers, Ruger
    Sturm, Ruger
    Sturm, Ruger & Company, Incorporated is a Southport, Connecticut-based firearm manufacturing company, better known by the shortened name Ruger. Sturm, Ruger produces bolt-action, semi-automatic, full-automatic, and single-shot rifles, shotguns, semi-automatic pistols, and single- and double-action...

     and Taurus
    Taurus (manufacturer)
    Forjas Taurus is a manufacturing conglomerate based in Porto Alegre, Brazil. Beginning as a tool and die manufacturer, the company now consists of divisions focusing on firearms, metals manufacturing, plastics, body armor, helmets, and civil construction.-History:Taurus produced its first...

    , started selling guns chambered in .454 Casull because it was popular due to its extreme power. It was finally commercialized in 1998, when SAAMI published its first standards for the cartridge.

Commercially developed wildcats

Though a cartridge technically has to not be developed commercially to be considered a wildcat, some commercial cartridges were developed by ammunition and firearm manufacturers by modifying existing cartridges – using essentially the same process used to make wildcats. Cartridges that are modified by being made longer (usually to make them more powerful) are for the most part only created commercially because of the difficulty of the process. One example of such a cartridge is the .357 Magnum
.357 Magnum
The .357 S&W Magnum , or simply .357 Magnum, is a revolver cartridge created by Elmer Keith, Phillip B. Sharpe, Colonel D. B. Wesson of firearms manufacturer Smith & Wesson, and Winchester. It is based upon Smith & Wesson's earlier .38 Special cartridge. The .357 Magnum cartridge was introduced in...

, which was developed from the .38 Special
.38 Special
The .38 Smith & Wesson Special is a rimmed, centerfire cartridge designed by Smith & Wesson. It is most commonly used in revolvers, although some semi-automatic pistols and carbines also use this round...

 in 1934 by firearms manufacturer Smith & Wesson
Smith & Wesson
Smith & Wesson is the largest manufacturer of handguns in the United States. The corporate headquarters is in Springfield, Massachusetts. Founded in 1852, Smith & Wesson's pistols and revolvers have become standard issue to police and armed forces throughout the world...

.
  • .38-40. One of the oldest wildcats, the .38-40, introduced by Winchester Repeating Arms Company
    Winchester Repeating Arms Company
    The Winchester Repeating Arms Company was a prominent American maker of repeating firearms, located in New Haven, Connecticut. The Winchester brand is today used under license by two subsidiaries of the Herstal Group, Fabrique Nationale of Belgium and the Browning Arms Company of Morgan, Utah.-...

     in 1874, was made by necking down a .44-40. Actually a .401 in (10.2 mm) cartridge, the .38-40 had faded into obsolescence before being revived with the growing popularity of Cowboy action shooting
    Cowboy action shooting
    Cowboy Action Shooting , also known as Western Action Shooting or Single Action Shooting, is a competitive shooting sport that originated in California, USA, in the early 1980s...

    . The ballistics of the .38-40 are close to the those of the .40 S&W
    .40 S&W
    The .40 S&W is a rimless pistol cartridge developed jointly by major American firearms manufacturers Winchester and Smith & Wesson. The .40 S&W was developed from the ground up as a law enforcement cartridge designed to duplicate performance of the FBI's reduced velocity 10mm cartridge which could...

    .
  • .221 Fireball. This cartridge was developed by Remington Arms
    Remington Arms
    Remington Arms Company, Inc. was founded in 1816 by Eliphalet Remington in Ilion, New York, as E. Remington and Sons. It is the oldest company in the United States which still makes its original product, and is the oldest continuously operating manufacturer in North America. It is the only U.S....

     for the XP-100
    Remington XP-100
    The Remington XP-100 is a bolt action pistol produced by Remington Arms from 1963 to 1998. The XP-100 was one of the first handguns designed for long range shooting, and introduced the .221 Remington Fireball , which is still the fastest handgun cartridge ever produced by a major ammunition maker...

     pistol, which was a single shot bolt action pistol. The .221 Fireball was a necked back .222 Remington
    .222 Remington
    The .222 Remington aka the Triple Deuce/Triple Two/Treble Two is a centerfire rifle cartridge introduced in 1950, and was the first commercial rimless .22 cartridge made in the United States...

    , designed for greater efficiency in the 10 in (25 cm) barrel of the XP-100. Even loaded with a smaller load of faster powder for the short barrel, the .221 Fireball lived up to its name, with a massive muzzle flash; the performance, however, was unheard of for its day: over 2700 feet per second (885 m/s) out of the short XP-100 barrel. It remains the fastest SAAMI approved handgun cartridge, and the cartridge is so efficient and accurate that it has been chambered in rifles as well.
  • .22 Remington Jet
    .22 Remington Jet
    The .22 Remington Jet is a .22 in American centerfire revolver and rifle cartridge....

    . This cartridge was developed by Remington
    Remington Arms
    Remington Arms Company, Inc. was founded in 1816 by Eliphalet Remington in Ilion, New York, as E. Remington and Sons. It is the oldest company in the United States which still makes its original product, and is the oldest continuously operating manufacturer in North America. It is the only U.S....

     for a Smith & Wesson Model 53 revolver and a Marlin Model 62 lever action rifle, but the rifle was never produced in this calibre. The .22 Remington Jet was a necked down .357 Magnum case.]]. The .22 Jet is no longer manufactured by Remington or other commercial manufacturers.
  • .357 SIG
    .357 SIG
    The .357 SIG pistol cartridge is the product of Swiss-German firearms manufacturer SIG-Sauer, in cooperation with the American ammunition manufacturer Federal Cartridge. While it is based on a .40 S&W case necked down to accept bullets, the .357 SIG brass is slightly longer...

    . This now-popular pistol cartridge was developed by Swiss weapons company Sig Sauer
    Schweizerische Industrie Gesellschaft
    Schweizerische Industrie Gesellschaft , or SIG, is the former name of SIG Holding AG, a Swiss company that has been active in various businesses during its more than 150 years of operation. Since the year 2000 the Society has undergone strategic refocus, concentrating on its core compentence in...

     in an attempt to produce ballistics matching the powerful .357 Magnum
    .357 Magnum
    The .357 S&W Magnum , or simply .357 Magnum, is a revolver cartridge created by Elmer Keith, Phillip B. Sharpe, Colonel D. B. Wesson of firearms manufacturer Smith & Wesson, and Winchester. It is based upon Smith & Wesson's earlier .38 Special cartridge. The .357 Magnum cartridge was introduced 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...

     load, but in a semi-automatic pistol cartridge. The cartridge was made by necking down and slightly stretching the .40 S&W
    .40 S&W
    The .40 S&W is a rimless pistol cartridge developed jointly by major American firearms manufacturers Winchester and Smith & Wesson. The .40 S&W was developed from the ground up as a law enforcement cartridge designed to duplicate performance of the FBI's reduced velocity 10mm cartridge which could...

     case, which itself derived from the 10 mm Auto
    10 mm Auto
    The 10mm Auto is a semi-automatic pistol cartridge developed by Jeff Cooper and introduced in 1983 for the Bren Ten pistol. It was initially produced by ammunitions manufacturer FFV Norma AB of Åmotfors, Sweden.Although it was selected by the F.B.I. for use in the field following the 1986 F.B.I...

    .
  • .400 Corbon
    .400 Corbon
    The .400 Corbon is an automatic pistol cartridge developed by Cor-Bon in 1997. It was created to mimic the ballistics of the powerful 10 mm Auto cartridge by means of a .45 ACP case, necked down to .40 caliber with a 25 degree shoulder....

    . This cartridge was designed to produce 10 mm Auto
    10 mm Auto
    The 10mm Auto is a semi-automatic pistol cartridge developed by Jeff Cooper and introduced in 1983 for the Bren Ten pistol. It was initially produced by ammunitions manufacturer FFV Norma AB of Åmotfors, Sweden.Although it was selected by the F.B.I. for use in the field following the 1986 F.B.I...

     ballistics in a cartridge that could be chambered in a .45 ACP
    .45 ACP
    The .45 ACP , also known as the .45 Auto by C.I.P., is a cartridge designed by John Browning in 1904, for use in his prototype Colt semi-automatic .45 pistol and eventually the M1911 pistol adopted by the United States Army in 1911.-Design and history:The U.S...

     pistol with a simple barrel swap. It was made by necking a .45 ACP
    .45 ACP
    The .45 ACP , also known as the .45 Auto by C.I.P., is a cartridge designed by John Browning in 1904, for use in his prototype Colt semi-automatic .45 pistol and eventually the M1911 pistol adopted by the United States Army in 1911.-Design and history:The U.S...

     down to .40 (10 mm). Initially, no firearms were available in .400 Cor-Bon, but barrels in the new caliber were produced for the M1911
    M1911
    The M1911 is a single-action, semi-automatic, magazine-fed, and recoil-operated handgun chambered for the .45 ACP cartridge. John M. Browning designed the firearm which was the standard-issue side arm for the United States armed forces from 1911 to 1985. The M1911 is still carried by some U.S....

     pistol.
  • .41 Action Express
    .41 Action Express
    The .41 Action Express is a pistol cartridge developed in the 1980s to reproduce the performance of the .41 Magnum cartridge in semi-automatic pistols.-History:...

    . Developed in 1986 by Action Arms for the Jericho 941
    Jericho 941
    The Jericho 941 is a double action/single action semi-automatic pistol developed by Israel Weapon Industries and introduced to the market in 1990 as the Jericho 941. It was first imported into the US in 1990 by K.B.I., Inc. of Harrisburg, PA. It was later imported by O.F. Mossberg & Sons and named...

     pistol. It, like the .357 SIG, attempted to make a magnum-power cartridge for a semi-automatic pistol. It started with a .41 Magnum case and cut it down to fit in a semi-automatic pistol chambered for 9 x 19 mm
    9 mm Luger Parabellum
    The 9×19mm Parabellum cartridge was designed by Georg Luger and introduced in 1902 by the German weapons manufacturer Deutsche Waffen- und Munitionsfabriken for their Luger semi-automatic pistol...

    . The rim was then turned down to the same dimensions as the 9 x 19 mm, making it a rebated rim cartridge. This allowed a unique switch up to a larger caliber. The .41 AE never saw huge commercial success because of the creation of the similarly-powerful .40 S&W
    .40 S&W
    The .40 S&W is a rimless pistol cartridge developed jointly by major American firearms manufacturers Winchester and Smith & Wesson. The .40 S&W was developed from the ground up as a law enforcement cartridge designed to duplicate performance of the FBI's reduced velocity 10mm cartridge which could...

     in 1990.
  • .204 Ruger
    .204 Ruger
    The .204 Ruger is a centerfire rifle cartridge developed by Hornady and Ruger. At the time of its introduction in 2004, the .204 Ruger was the highest velocity commercially produced ammunition, and the only cartridge produced commercially for bullets of .204 inch/5 mm caliber.-Characteristics:The...

    . Introduced in 2004 by Ruger, in its time it held the title of fastest production cartridge with a velocity of 4225 ft/s (1290 m/s) with a 32 gr, .204 bullet from a 24 inches (609.6 mm) barrel. Intended as a varmint rifle
    Varmint rifle
    Varmint rifle is an American English term for a small-caliber firearm or high-powered air gun primarily used for varmint hunting — killing non-native or non-game animals such as rats, house sparrows, starling, crows, ground squirrels, gophers, jackrabbits, marmots, groundhogs, porcupine,...

     cartridge, the .204 was based on the .222 Remington Magnum
    .222 Remington Magnum
    The .222 Remington Magnum was a short-lived commercially produced cartridge derived from the .222 Remington. Originally developed for a US prototype military rifle in 1958, the cartridge was not adopted by the military, but was introduced commercially in sporting rifles.-Development:The .222 Rem....

    , which is slightly longer than the .223 Remington and offers about 5% more case capacity. Designed to have a very long point blank range, the factory loading offers impressive ballistics, 1.5 inches high at 150 yards (137.2 m), and 1.5 inches (38.1 mm) low at 277 yards (253.3 m).

Second (and later) generation wildcats

Some wildcats are based not on commercial rounds, but on other successful wildcats. The .308 x 1.5" Barnes, a wildcat from noted cartridge author Frank Barnes made by simply necking a .308 Winchester
.308 Winchester
The .308 Winchester is a rifle cartridge and is the commercial cartridge upon which the military 7.62x51mm NATO centerfire cartridge is based. The .308 Winchester was introduced in 1952, two years prior to the NATO adoption of the 7.62x51mm NATO T65...

 back to 1.5 inches (38.1 mm) in length (38.1 mm) is probably the best example of a wildcat that has spawned many other successful wildcats. The .308 x 1.5" case is available from a number of case manufacturers, and differs from a homemade .308 x 1.5" in that it has a small primer pocket, where the original .308 Winchester case has a larger primer pocket (the smaller primer is more suited to the smaller case capacity of the short round). There are at least 8 wildcats that are made from the small primer .308 x 1.5" brass, including some very successful benchrest
Benchrest shooting
Benchrest shooting is a sport in which very accurate and precise rifles are shot at paper targets from a rest or bench from a sitting position. Benchrest shooters are notoriously detail-oriented and constantly trying to further the accuracy potential of the rifle through experimentation. Nearly...

 rounds, including the Benchrest Remington family of cartridges, .22 BR, 6mm BR, 6.5 mm BR, 7 mm BR, .30 BR.

Another example is the .220 Russian
.220 Russian
The .220 Russian cartridge was developed in the late 1950s for deer hunting in Russia. It is a 7.62x39 cartridge necked down to hold a 5.6mm bullet. It was later adopted by Finland, and by around 1965 was being produced by SAKO and Lapua. When it was introduced to the United States, Sako, and...

, based on the 7.62 x 39 mm. Since nearly all 7.62 x 39 mm ammunition made in the 1970s used the complex to reload Berdan priming, and often 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...

 cases, it made a poor choice for wildcatting. The .220 Russian, however, was and still is readily available in Boxer primed, brass cases of high quality. The .220 Russian is still the parent cartridge of choice for the PPC line of cartridges, such as the .22 PPC and 6 mm PPC, even though there are far more PPC chambered firearms available than .220 Russian chamberings. Likewise, the PPC line of cartridges were the parent case of the 6.5 Grendel
6.5 Grendel
The 6.5 Grendel is a proprietary intermediate cartridge developed in 2002 by Arne Brennan . This cartridge is an improved version of the PPC cartridge family designed by Dr. Lou Palmisano and Ferris Pindell in 1974. The first 6.5mm member of the PPC cartridge family was created in 1984 by Dr...

, a long-range, high-energy cartridge for the AR-15 platform.

See also

  • Whisper Family of Firearm Cartridges
    Whisper Family of Firearm Cartridges
    The Whisper family of firearm cartridges is a group of wildcat cartridges developed in the early 1990s by J.D. Jones of SSK Industries. The Whisper Family was developed as a line of accurate, multi-purpose cartridges using relatively heavy rifle bullets for a given caliber in subsonic loads...

    , proprietary cartridges by J. D. Jones
  • Wildcats for Special Applications
  • .30-06 Springfield Wildcat Cartridges
    .30-06 Springfield Wildcat Cartridges
    Wildcat cartridges are firearms cartridges whose dimensions have been modified. Usually these modifications are with an eye toward improved performance, either measurable or not. This article deals with wildcat cartridges which result from a simple necking down or up of the original .30-06...


External links

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