.40 S&W
The .40 S&W is a rimless
Rim (firearms)
A rim is an external flange that is machined, cast, molded, stamped or pressed around the bottom of a firearms cartridge. The rim may serve a number of purposes, the most common being as the place for the extractor to engage...

 pistol cartridge developed jointly by major American firearm
A firearm is a weapon that launches one, or many, projectile at high velocity through confined burning of a propellant. This subsonic burning process is technically known as deflagration, as opposed to supersonic combustion known as a detonation. In older firearms, the propellant was typically...

s manufacturers Winchester
U.S. Repeating Arms Company
The U.S. Repeating Arms Company. Inc. is the current business name of the Winchester Repeating Arms Company, famous for making Winchester rifles....

 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 be retrofitted into medium-frame (9mm size) automatic handguns. It uses .40-inch (10.16 mm) diameter bullets ranging in weight from 125 to 200 grains (9 g to 13 g). A number of .40 S&W loads with hollowpoint bullets offer a good combination of expansion and penetration.


In the aftermath of the 1986 FBI Miami shootout, the FBI started the process of testing 9mm and .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...

 ammunition in preparation to replace its standard issue revolver with a semi-automatic pistol. The semi-automatic pistol offered two advantages over the revolver: 1) the semi-automatic offered increased ammunition capacity, and 2) it was easier to reload during a gunfight. The FBI was satisfied with performance of its .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...

 +P 158 gr LSWCHP cartridge ("FBI load") based on decades of dependable performance. Ammunition for the new semi-automatic pistol had to deliver terminal performance equal or superior to the .38 Special FBI Load. The FBI developed a series of practically oriented tests involving eight test events that reasonably represented the kinds of situations that FBI agents commonly encounter in shooting incidents.

During tests of 9mm and .45 ACP ammunition, FBI Firearms Training Unit Special Agent in Charge John Hall decided to include tests of the 10mm cartridge, supplying his personally owned Colt Delta Elite
Colt Delta Elite
-See also:*Bren Ten, the first pistol chambered for 10mm Auto*Glock 20, another relatively successful pistol chambered for 10mm Auto*M1911A1, the design from which the Delta Elite was created*Kimber Eclipse, another 1911-style handgun chambered in 10mm Auto...

 10mm semi-automatic, and personally handloading 10mm ammunition. The FBI's tests revealed that a 170 gr JHP 10mm bullet, propelled between 900–1000 ft/s (274.3–304.8 m/s), achieved desired terminal performance without the heavy recoil associated with conventional 10mm ammunition (1300–1400 ft/s (396.2–426.7 m/s)). The FBI contacted Smith & Wesson and requested it to design a handgun to FBI specifications, based on the existing large-frame S&W 4506 .45 ACP handgun, that would reliably function with the FBI's reduced velocity 10mm ammunition. During this collaboration with the FBI, S&W realized that downloading the 10mm full power to meet the FBI medium velocity specification meant less powder and more airspace in the case. They found that by removing the airspace they could shorten the 10mm case enough to fit within their medium-frame 9mm handguns and load it with a 180 gr JHP bullet to produce ballistic performance identical to the FBI's reduced velocity 10mm cartridge. S&W then teamed with Winchester to produce a new cartridge, the .40 S&W. It uses a small pistol primer whereas the 10mm cartridge uses a large pistol primer.

The .40 S&W cartridge debuted January 17, 1990 along with the new Smith & Wesson Model 4006 pistol, although it was several months before the pistols were available for purchase. Austrian manufacturer Glock Ges.m.b.H. beat Smith & Wesson to the dealer shelves in 1990, with pistols chambered in .40 S&W (the Glock 22 and 23) which were announced a week before the 4006. Glock's rapid introduction was aided by its engineering of a pistol chambered in 10 mm Auto, the Glock 20, only a short time earlier. Since the .40 S&W uses the same bore diameter and case head as the 10 mm Auto, it was merely a matter of adapting the 10 mm design to the shorter 9x19mm frames. The new guns and ammunition were an immediate success.

The 40 S&W case length and overall cartridge length are shortened, but other dimensions except case web and wall thickness remain identical to the 10mm Auto. Both cartridges headspace on the mouth of the case. Thus in a semi-auto they are not interchangeable. Fired from a 10mm pistol the .40 Smith & Wesson cartridge will headspace on the extractor and the bullet will jump a .142 inch freebore just like a .38 Special fired from a .357 Magnum pistol. If the cartridge is not held by the extractor, the chances for a ruptured primer are great. Smith and Wesson does make a double action 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...

 that can fire either at will using moon clip
Moon clip
A moon clip is a ring-shaped or star-shaped piece of metal designed to hold multiple cartridges together as a unit, for simultaneous insertion and extraction from a revolver cylinder...

s. A single-action revolver in the .38-40 chambering can also be modified to fire the .40 or the 10 mm if it has an extra cylinder. Most .40 caliber handguns can be easily converted to 9mm for cheaper target shooting with a simple barrel and magazine swap.

Israel Military Industries
Israel Weapons Industries , formerly the "Magen" division of the Israel Military Industries Ltd. is an Israeli firearms manufacturer. In 2005, the Small Arms Division of IMI was privatized....

 attempted a similar cartridge in the 1980s, called the .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:...

 (or .41 AE) 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. This cartridge was based on a new proprietary case with a 9mm base and 41 caliber suitable main case body. The .41 AE is ballistically similar to the .40 S&W, to the point that some reloading manuals suggest using .40 S&W load data in the .41 AE. The .41 AE was a poor design because the small rim and larger and higher energy .41 case beats the 9mm rim/base up badly. Case life for reloading is relatively short. The .41 AE is for all intents and purposes, now an obsolete and difficult to obtain caliber. The .41 AE uses 0.41 inches (10.4 mm) bullets, whereas the .40 S&W uses 0.4 inches (10.2 mm) bullets. However, as it lacks the backing of ammunition manufacturers in making .410 caliber bullets suited to semi-automatic pistols, the .41 AE has not achieved widespread popularity.

Cartridge dimensions

The .40 S&W has 1.25 ml
pic|200px|right|thumb|One litre is equivalent to this cubeEach side is 10 cm1 litre water = 1 kilogram water The litre is a metric system unit of volume equal to 1 cubic decimetre , to 1,000 cubic centimetres , and to 1/1,000 cubic metre...

 (19.3 grains
Grain (measure)
A grain is a unit of measurement of mass that is nominally based upon the mass of a single seed of a cereal. From the Bronze Age into the Renaissance the average masses of wheat and barley grains were part of the legal definition of units of mass. However, there is no evidence of any country ever...

 H2O) cartridge case capacity.
.40 S&W maximum C.I.P. cartridge dimensions. All sizes in millimeters (mm).

The common rifling
Rifling is the process of making helical grooves in the barrel of a gun or firearm, which imparts a spin to a projectile around its long axis...

 twist rate for this cartridge is 406 mm (1 in 16 in), 6 grooves, ∅ lands = 9.91 mm, ∅ grooves = 10.17 mm, land width = 3.05 mm and the primer type
Percussion cap
The percussion cap, introduced around 1830, was the crucial invention that enabled muzzleloading firearms to fire reliably in any weather.Before this development, firearms used flintlock ignition systems which produced flint-on-steel sparks to ignite a pan of priming powder and thereby fire the...

 is small pistol. According to the official C.I.P. (Commission Internationale Permanente Pour L'Epreuve Des Armes A Feu Portative) guidelines the .40 S&W case can handle up to 225 MPa (32,633 psi) piezo pressure. In C.I.P. regulated countries every pistol cartridge combo has to be proofed at 130% of this maximum C.I.P. pressure to certify for sale to consumers.
Saami or SAAMI can stand for:*Sami people*Sami languages*Sporting Arms and Ammunition Manufacturers' Institute...

 pressure limit for the .40 S&W is set at 241.32 MPa (35,000 psi
Pounds per square inch
The pound per square inch or, more accurately, pound-force per square inch is a unit of pressure or of stress based on avoirdupois units...

), piezo pressure.


The .40 S&W cartridge has been successful with law enforcement agencies in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

, and Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

. While possessing nearly identical accuracy, drift and drop, it has an energy advantage over the 9 mm Parabellum, and with a more manageable recoil than the 10 mm Auto cartridge. Marshall & Sanow (and other hydrostatic shock proponents) contend that with good JHP bullets, the more energetic loads for the .40 S&W can also create hydrostatic shock
Hydrostatic shock
Hydrostatic shock or hydraulic shock describes the observation that a penetrating projectile can produce remote wounding and incapacitating effects in living targets through a hydraulic effect in their liquid-filled tissues, in addition to local effects in tissue caused by direct impact...

 in human-sized living targets.

Based on ideal terminal ballistic performance in ordnance gelatin during lab testing in the late 1980s and early 1990s, the .40 S&W earned status as "the ideal cartridge for personal defense and law enforcement". Apart from the imperfect relationship between ordnance gelatin ballistics and actual stopping power, critics pointed to the reduced power of the round compared with the 10 mm Auto it was based on. The energy of the .40 S&W exceeds standard-pressure .45 ACP loadings, generating between 350 ft.lb and 500 ft.lb of energy, depending on bullet weight. Both the .40 S&W and the 9 mm Parabellum operate at a 35,000 psi (240 MPa) SAAMI maximum, compared to a 21,000 psi (150 MPa) maximum for .45 ACP.

The mainstay for military use in the western world largely remains the preserve of the 9 mm Parabellum, or for a few US special forces
Special forces
Special forces, or special operations forces are terms used to describe elite military tactical teams trained to perform high-risk dangerous missions that conventional units cannot perform...

, .45 ACP in their respective adopted handguns. The United States Coast Guard
United States Coast Guard
The United States Coast Guard is a branch of the United States Armed Forces and one of the seven U.S. uniformed services. The Coast Guard is a maritime, military, multi-mission service unique among the military branches for having a maritime law enforcement mission and a federal regulatory agency...

, which also performs Maritime Law Enforcement duties and Military duties, has adopted the Sig Sauer P229R DAK in .40 S&W as their standard sidearm. The Beretta M9, 9mm pistol is also in service with some U.S. Coast Guard units.

The .40 S&W was originally loaded at subsonic velocity (around 980 ft/s (298.7 m/s)) with a 180 grain bullet. Since its introduction, various loads have been created, with the majority being either 155 gr, 165 gr or 180 gr. However, there are some bullets with weights as light as 135 grain and as heavy as 200 gr. Cor-Bon and Winchester both offer a 135 gr JHP and Cor-Bon also offers a 140 gr Barnes XPB hollow-point. Double Tap Ammo, based out of Cedar City, Utah
Cedar City, Utah
As of the census of 2000, there were 20,527 people, 6,486 households, and 4,682 families residing in the city. The population density was 1,021.8 people per square mile . There were 7,109 housing units at an average density of 353.9 per square mile...

 loads a 135 gr Nosler JHP, a 155 gr, 165 gr and 180 gr Speer Gold Dot hollow-point (marketed as "Bonded Defense"), a 180gr Hornady XTP JHP, and three different 200gr loads included a 200 gr Full Metal Jacket (FMJ), a 200 gr Hornady XTP JHP and Double Tap's own 200 gr WFNGC (Wide Flat Nose Gas check
Gas check
A gas check is a device used in some types of firearms ammunition. Gas checks are used when non-jacketed bullets are used in high pressure cartridges, to prevent the buildup of lead in the barrel and aid in accuracy.-Construction:...

) hard cast lead bullet; the latter specifically designed for hunting and woods carry applications.

The table below shows common performance parameters for several .40 S&W loads. Bullet weights from 135 to 180 grains are common. Loads are available with energies from just over 360 ft.lbf to over 550 ft.lbf, and penetration depths from 9.8 inches (248.9 mm) to 25 inches (635 mm) are available for various applications and risk assessments.

Manufacturer Load Mass (grains) Velocity (ft/s) Energy (ft·lbf) Expansion (inches) Penetration (inches) PC (cu in) TSC (cu in)
Cor-Bon JHP 135 1300 507 0.56 9.8 2.4 69.1
Warrior Arms T.A.C. JHP 135 1440 622 0.55 10.9 4.8 72.8
Double Tap Gold Dot JHP 155 1275 559 0.76 13.0 5.9 48.5 (est)
Federal HydraShok JHP 155 1140 447 0.68 13.3 4.8 47.9
Warrior Arms T.A.C. JHP 155 1286 569 0.75 13.1 4.9 47.7
Remington Golden Saber JHP 165 1150 485 0.68 12.0 4.4 41.1
Winchester Ranger SXT 180 990 392 0.72 13.0 5.3 29.1
Winchester FMJ 180 950 361 0.40 25.0 3.1 14.6


Expansion: expanded bullet diameter (ballistic gelatin).

Penetration: penetration depth (ballistic gelatin).

PC: permanent cavity volume (ballistic gelatin, FBI method).

TSC: temporary stretch cavity volume (ballistic gelatin).

Case failure reports

The .40 S&W has been noted in a number of cartridge case failures, particularly in older Glock pistols due to the relatively large area of unsupported case head in those barrels, given its high working pressure. The feed ramp on the Glock .40 S&W pistols is larger than on other Glocks, which leaves the rear bottom of the case unsupported, and it is in this unsupported area that the cases fail. Most, but not all, of the failures have occurred with reloaded or remanufactured ammunition. Cartridges loaded at or above the SAAMI pressure, or slightly oversized cases which fire slightly out of battery
Out-of-battery refers to the status of a weapon before the action has returned to the normal firing position. The term originates from artillery, referring to a gun that fires before it has been pulled back into its firing position in a gun battery....

 are often considered to be the cause of these failures. Many competition shooters who reload for the .40 S&W will utilize a heavier than factory tension recoil spring to increase the lock time of the slide and prevent potential issues with early slide lock release. These failures are commonly referred to as "kaBooms" or "kB!" for short. While these case failures do not often injure the person holding the pistol, the venting of high pressure gas tends to eject the magazine out of the magazine well in a spectacular fashion, and usually destroys the pistol. In some cases, the barrel will also fail, blowing the top of the chamber off.

While the .40 S&W is far from the only cartridge to suffer from case failures, it is more susceptible for a number of reasons. The .40 S&W works at relatively high pressures (33,000 psi/230 MPa typical, but 35,000 psi/240 MPa SAAMI max). Since the .40 S&W is a wide cartridge for its length, and is often adapted to frames designed for the equally long but narrower 9x19mm cartridge, the length of the feed ramp must be longer to provide the same angle, which causes the feed ramp to extend into the chamber. This in turn leaves more of the case head unsupported. While this is not necessarily unsafe, it does reduce the margin of safety. When exacerbated by out of battery firing (leaving even more case head exposed) and potentially weakened brass (due to reloading) these factors appear to lead to the higher incidents of chamber failure. The number of case failures in the .40 S&W is serious enough that Accurate Arms no longer recommends reloading of .40 S&W cartridges for firearms without complete case head support.

In late 1995, Federal Cartridge of Anoka, Minnesota undertook a redesign of their .40 S&W cartridge case to strengthen internally the area of the case web. While no one at Federal will address this for the record, it has been suggested that this move was dictated by the popularity of the .40 S&W Glocks, and Federal's attempt to hedge against head/web ruptures with any of their .40 S&W ammunition.

Federal .40 S&W rounds which may contain suspect casings may be identified as follows:
Lot number consists of 10 characters (mostly numbers). In the 7th position, there may be a number or a letter. If there is a number in that position, the ammo was manufactured with the old style (possibly defective) brass. If it contains the letter Y (1995) or R (1996), the ammo has the redesigned casing and should be okay. If the letter H appears, then check the next three digits (the last three in the lot number). Ammo lot numbers H244 or below have the old style casings. Lots H245 and above have the new style casings.

This information was provided by Federal Cartridge Company in September 1996.

Writer Walt Rauch who first brought forth information that bullet set-back such as often occurs in administrative unloading/loading) in the .40 S&W could raise pressures exponentially. Rauch published some specific information on this set-back issue in the May/June 2004 Police and Security News, in a feature entitled Why Guns Blow Up! "The simple chambering and rechambering of a cartridge does push the bullet back into its case."

Hirtenberg Ammunition Company of Austria (at the request of GLOCK, Inc.) determined that, with a .40 caliber cartridge, pushing the bullet back into the case 1/10 of an inch doubled the chamber pressure. This is higher than a proof load. This can occur with but one chambering since it is dependent on how well the case was crimped or sealed to the bullet.


  • .40
  • .40 Smith
  • .40 S&W
  • .40 Auto
  • .40 Short & Wimpy or Short & Weak (a derogatory comparison to the parent 10 mm Auto cartridge)
  • .40 Slow & Weighty (a reference to a proposed 200 grain offering with less recoil and high effectiveness)
  • .40 caliber or "Forty cal"
  • .40 Liberty (promoted by L. Neil Smith
    L. Neil Smith
    L. Neil Smith , also known to readers and fans as El Neil, is a libertarian science fiction author and political activist. He was born on May 12, 1946 in Denver...

     as part of a boycott
    A boycott is an act of voluntarily abstaining from using, buying, or dealing with a person, organization, or country as an expression of protest, usually for political reasons...

     of Smith & Wesson for making an agreement with the U.S. government under President Bill Clinton
    Bill Clinton
    William Jefferson "Bill" Clinton is an American politician who served as the 42nd President of the United States from 1993 to 2001. Inaugurated at age 46, he was the third-youngest president. He took office at the end of the Cold War, and was the first president of the baby boomer generation...

  • 10 mm Kurz (10 mm Short)

See also

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