.45 ACP
Overview
 
The .45 ACP (Automatic Colt Pistol), also known as the .45 Auto by C.I.P., is a cartridge designed by John Browning
John Browning
John Moses Browning , born in Ogden, Utah, was an American firearms designer who developed many varieties of military and civilian firearms, cartridges, and gun mechanisms, many of which are still in use around the world...

 in 1904, for use in his prototype Colt
Colt's Manufacturing Company
Colt's Manufacturing Company is a United States firearms manufacturer, whose first predecessor corporation was founded in 1836 by Sam Colt. Colt is best known for the engineering, production, and marketing of firearms over the later half of the 19th and the 20th century...

 semi-automatic .45 pistol and eventually the M1911 pistol adopted by the United States Army
United States Army
The United States Army is the main branch of the United States Armed Forces responsible for land-based military operations. It is the largest and oldest established branch of the U.S. military, and is one of seven U.S. uniformed services...

 in 1911.
The U.S. Cavalry
United States Cavalry
The United States Cavalry, or U.S. Cavalry, is the designation of the mounted force of the United States Army. The role of the U.S. Cavalry is reconnaissance, security and mounted assault. Cavalry has served as a part of the Army forces in every war in which the United States has participated...

 had been buying and testing various handguns in the late 1890s and early 20th century. The .45
.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...

 Colt Single Action Army
Colt Single Action Army
The Colt Single Action Army is a single action revolver with a revolving cylinder holding six metallic cartridges. It was designed for the U.S...

 had largely been replaced, even by some double action versions of the same.
Encyclopedia
The .45 ACP (Automatic Colt Pistol), also known as the .45 Auto by C.I.P., is a cartridge designed by John Browning
John Browning
John Moses Browning , born in Ogden, Utah, was an American firearms designer who developed many varieties of military and civilian firearms, cartridges, and gun mechanisms, many of which are still in use around the world...

 in 1904, for use in his prototype Colt
Colt's Manufacturing Company
Colt's Manufacturing Company is a United States firearms manufacturer, whose first predecessor corporation was founded in 1836 by Sam Colt. Colt is best known for the engineering, production, and marketing of firearms over the later half of the 19th and the 20th century...

 semi-automatic .45 pistol and eventually the M1911 pistol adopted by the United States Army
United States Army
The United States Army is the main branch of the United States Armed Forces responsible for land-based military operations. It is the largest and oldest established branch of the U.S. military, and is one of seven U.S. uniformed services...

 in 1911.

Design and history

The U.S. Cavalry
United States Cavalry
The United States Cavalry, or U.S. Cavalry, is the designation of the mounted force of the United States Army. The role of the U.S. Cavalry is reconnaissance, security and mounted assault. Cavalry has served as a part of the Army forces in every war in which the United States has participated...

 had been buying and testing various handguns in the late 1890s and early 20th century. The .45
.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...

 Colt Single Action Army
Colt Single Action Army
The Colt Single Action Army is a single action revolver with a revolving cylinder holding six metallic cartridges. It was designed for the U.S...

 had largely been replaced, even by some double action versions of the same. The Cavalry had fielded some double action revolvers in .38 Long Colt
.38 Long Colt
The .38 Long Colt is a cartridge introduced by Colt's Manufacturing Company in 1875, and was adopted as a standard military pistol cartridge by the United States Army in 1892 for the Colt New Army M1892 Revolver. It is slightly more powerful than the .38 Short Colt, or .38 SC. The .38 Long Colt...

. They determined that the .38-caliber round was significantly less effective against determined opponents, such as the warriors encountered in the Moro Rebellion
Moro Rebellion
The Moro Rebellion was an armed military conflict between Moro revolutionary groups in the Mindanao, Sulu, and Palawan and the United States military which took place in the Philippines as early as between 1899 to 1913, following the Spanish-American War in 1898...

 of the Philippine–American War, than the .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...

. The current issue rifle at the time, the .30-40 Krag
.30-40 Krag
The .30-40 Krag was a cartridge developed in the early 1890s to provide the U.S. armed forces with a smokeless powder cartridge suited for use with modern small-bore repeating rifles to be selected in the 1892 small arm trials...

, had also failed to stop Moro warriors effectively; the British
United Kingdom of Great Britain and Ireland
The United Kingdom of Great Britain and Ireland was the formal name of the United Kingdom during the period when what is now the Republic of Ireland formed a part of it....

 had similar issues switching to 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...

, which resulted in the development of the Dum-dum bullet. This experience, and the Thompson-LaGarde Tests
Thompson-LaGarde Tests
The Thompson-LaGarde Tests were a series of tests conducted in 1904 to determine which caliber should be used in new military handguns. The US Army's fighting men had considerable difficulty stopping the Moro warriors and other combatants with the .38 Long Colt, and the Army began to consider the...

 of 1904 led the Army and the Cavalry to decide that a minimum of .45-caliber was required in the new handgun. Thompson and Major Louis Anatole LaGarde of the Medical Corps arranged tests on cadavers and animal remains in the Chicago stockyards, resulting in a finding that the .45 was the most effective pistol cartridge. They noted, however, that training was critical to make sure a soldier could score a hit in a vulnerable part of the body.

Colt had been working with Browning on a .41-caliber
10 mm caliber
This article lists firearm cartridges which have a bullet in the caliber range.*Length refers to the cartridge case length.*OAL refers to the overall length of the cartridge.All measurements are in mm .-Pistol cartridges:...

 cartridge in 1904, and in 1905 when the Cavalry asked for a .45-caliber equivalent Colt modified the pistol design to fire a .45-caliber version of the prototype .41-caliber round. The result from Colt was the Model 1905 and the new .45 ACP cartridge. The original round that passed the testing fired a 200 grain (13 g) bullet at 900 ft/s (275 m/s), but after a number of rounds of revisions between Winchester Repeating Arms
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.-...

, Frankford Arsenal
Frankford Arsenal
The Frankford Arsenal was a United States Army ammunition plant located adjacent to the Bridesburg neighborhood of Northeast Philadelphia, Pennsylvania, north of the original course of Frankford Creek.-History:...

, and Union Metallic Cartridge
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....

, it ended up using a 230-grain (15 g) bullet fired at about 850 ft/s (260 m/s). The resulting .45-caliber cartridge, named the .45 ACP, was similar in performance to the .45 Schofield
.45 Schofield
The .45 Schofield or .45 Smith & Wesson is a revolver cartridge developed by Smith & Wesson for their S&W Model 3 American top-break revolver. It is similar to the .45 Colt round though shorter and with a slightly larger rim, and will generally work in revolvers chambered for that cartridge...

 cartridge, and only slightly less powerful (but significantly shorter) than the .45 Colt cartridges the Cavalry was using.

By 1906 bids from six makers were submitted, among them Browning's design, submitted by Colt. Only DWM
Deutsche Waffen und Munitionsfabriken
Deutsche Waffen- und Munitionsfabriken Aktien-Gesellschaft , known as DWM, was an arms company in Imperial Germany created in 1896 when Ludwig Loewe & Company united its weapons and ammunition production facilities within one company...

, Savage
Savage Arms
The Savage Arms Company is a firearms manufacturing company based in Westfield, Massachusetts, with a division located in Canada. The company makes a variety of rimfire and centerfire rifles, as well as marketing the Stevens single-shot rifles and shotguns...

, and Colt made the first cut. DWM, which submitted two Luger P08 pistols adapted to the .45 ACP cartridge, withdrew from testing after the first round of tests, for unspecified reasons. One of the DWM pistols, serial number 1, was destroyed in testing; the remaining instance, serial number 2, is considered one of the most desirable collectors handguns in existence.

In the second round of evaluations in 1910, the Colt design passed the extensive testing with no failures, while the Savage design suffered 37 stoppages or parts failures. The resulting Colt design was adopted as the Model 1911.

The cartridge/pistol combination was quite successful but not satisfactory for U.S. military purposes. Over the next few years a series of improved designs were offered, culminating in the adoption in 1911 of the "Cal. .45 Automatic Pistol Ball Cartridge, Model of 1911", a 1.273 inch cartridge with a bullet weight of 230 grains. The very first production, at Frankford Arsenal, was marked "F A 8 11", for the August 1911 date.

The cartridge was designed by John Browning of Colt, but the most swaying influence over the choice of cartridge for the new Army pistol came from Army Ordnance member Gen. John T. Thompson
John T. Thompson
John Taliaferro Thompson, , was a United States Army officer best remembered as the inventor of the Thompson submachine gun.-Early life:...

 (who would later design the famed Thompson submachine gun
Thompson submachine gun
The Thompson is an American submachine gun, invented by John T. Thompson in 1919, that became infamous during the Prohibition era. It was a common sight in the media of the time, being used by both law enforcement officers and criminals...

 around the .45 ACP cartridge). Thompson insisted on a real "man stopper" pistol, following the poor showing of the Army's .38 Long Colt pistols during the Philippine-American War (1899–1902).

Cartridge dimensions

(Diagram not to scale)

The .45 ACP has 1.62 ml
Litre
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...

 (25 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.

.45 ACP maximum C.I.P. cartridge dimensions. All sizes in millimeters (mm).

The common rifling
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 406mm (1 in 16 in), 6 grooves, Ø lands = 11.23mm, Ø grooves = 11.43mm, land width = 3.73mm 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 large pistol.
The cartridge headspaces on the mouth of the case at the L3 datum reference.

According to the official Commission Internationale Permanente pour l'Epreuve des Armes à Feu Portatives
Commission Internationale Permanente pour l'Epreuve des Armes à Feu Portatives
The Commission Internationale Permanente pour l'Epreuve des Armes à Feu Portatives is an international organisation whose members are 14 states, mainly European....

 guidelines the .45 ACP case can handle up to 130 MPa (18,854.9 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. The SAAMI
Sporting Arms and Ammunition Manufacturers' Institute
The Sporting Arms and Ammunition Manufacturers' Institute is an association of American firearms and ammunition manufacturers...

 pressure limit for the .45 ACP is set at 21000 psi (144.8 MPa), piezo pressure, while
the SAAMI pressure limit for the .45 ACP +P is set at 23000 psi (158.6 MPa), piezo pressure.

Performance

The .45 ACP is an effective combat pistol cartridge that combines accuracy and stopping power
Stopping power
Stopping power is a colloquial term used to describe the ability of a firearm or other weapon to cause a penetrating ballistic injury to a target, human or animal, sufficient to incapacitate the target where it stands....

 for use against human targets. The cartridge also has relatively low muzzle blast and flash, as well as moderate recoil
Recoil
Recoil is the backward momentum of a gun when it is discharged. In technical terms, the recoil caused by the gun exactly balances the forward momentum of the projectile and exhaust gasses, according to Newton's third law...

. The .45 ACP also operates at a relatively low maximum chamber pressure rating of 21,000 psi (145 MPa) (compared to 35,000 psi/240 MPa for 9mm Parabellum and .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...

, 37,500 psi/260 MPa for 10mm Auto, 40,000 psi/280 MPa for .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...

), which due to a low bolt thrust
Bolt thrust
Bolt thrust or breech pressure is a term used in internal ballistics and firearms that describes the amount of rearward force exerted by the propellant gases on the bolt or breech of a firearm action or breech when a projectile is fired...

 helps extend service life of weapons in which it is fired.

Like many pistol cartridges, it is a low-velocity round, and thus ineffective against body armor. Another drawback for large scale military operations is the cartridge's large size, weight, the increased material cost of manufacture compared to the smaller 9×19mm Parabellum cartridge, and lack of compliance with Standardization Agreements pertaining to handgun ammunition currently enacted between the US and many of its allies.

Even in its non-expanding 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...

 (FMJ) version, the .45 ACP cartridge has a reputation for effectiveness against human targets because its large diameter creates a deep and substantial permanent wound channel which lowers blood pressure more rapidly. The wounding potential of bullets is often characterized in terms of a bullet's expanded diameter, penetration depth, and energy. Bullet energy for .45 ACP loads varies from roughly 350 to 500 ft·lbf (474.5 to 677.9 J).

The table below shows common performance parameters for several .45 ACP loads. Bullet weights ranging from 185 to 230 grains are common. Penetration depths from 11 inches to over 27 inches are available for various applications and risk assessments.
Manufacturer Load Mass Velocity Energy Expansion Penetration PC TSC
Federal HydraShok JHP 230 gr 850 ft/s (259.1 m/s) 369 ft-lb (500.3 J) 0.78 in (19.8 mm) 12 in (304.8 mm) 5.73 cu in (94 ml) 28.4 cu in (465.8 ml)
Remington Golden Saber JHP 230 gr 875 ft/s (266.7 m/s) 391 ft-lb (530.1 J) 0.75 in (19.1 mm) 14.3 in (363.2 mm) 6.32 cu in (103.6 ml) 25.4 cu in (416.6 ml)
Cor-Bon JHP 185 gr 1150 ft/s (350.5 m/s) 544 ft-lb (737.6 J) 0.7 in (17.8 mm) 11.3 in (287 mm) 4.35 cu in (71.3 ml) 28.6 cu in (469 ml)
Winchester Silvertip JHP 185 gr 1000 ft/s (304.8 m/s) 411 ft-lb (557.2 J) 0.79 in (20.1 mm) 12 in (304.8 mm) 5.88 cu in (96.4 ml) 30.2 cu in (495.3 ml)
Winchester Ranger SXT 230 gr 900 ft/s (274.3 m/s) 414 ft-lb (561.3 J) 0.78 in (19.8 mm) 13 in (330.2 mm) 6.21 cu in (101.8 ml) 25.4 cu in (416.6 ml)
Remington FMJ 230 gr 835 ft/s (254.5 m/s) 356 ft-lb (482.7 J) 0.45 in (11.4 mm) 27 in (685.8 mm) 4.29 cu in (70.4 ml) 9 cu in (147.6 ml)


Key:

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).


The .45 ACP's combination of stopping power and controlled penetration makes it practical for police use, although numerous issues, including the resulting decrease in magazine capacity and the larger size and weight of pistols chambered in this caliber, have led more police departments in the USA to adopt sidearms in 9×19mm, .40 S&W, and .357 SIG. Many modern versions of .45 ACP handguns have magazines capable of holding as many as 14 cartridges, such as the HS2000 or Glock model 21
Glock pistol
The Glock pistol, sometimes referred to by the manufacturer as Glock "Safe Action" Pistol, is a series of semi-automatic pistols designed and produced by Glock Ges.m.b.H., located in Deutsch-Wagram, Austria. The company's founder, engineer Gaston Glock, had no experience with firearm design or...

, though this greatly increases the pistol's bulk and with that lowers maneuverability.

Many US tactical police units still use the .45 pistol round, including the FBI's Hostage Rescue Team. While high capacity firearms are available in .45 ACP, the greater length and diameter of the .45 ACP means that the grip of the pistol must be longer and wider than the grip of a comparable pistol of a smaller caliber; this increase in grip size can make the pistol difficult to use for shooters with smaller hands.

Today, most NATO militaries use sidearms chambered for the 9×19mm Parabellum cartridge, but the effectiveness of the .45 ACP cartridge has ensured its continued popularity with large caliber sport shooters, especially in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

. In addition, select military and police units around the world still use firearms firing the .45 ACP. In 1985 the .45 ACP M1911A1 pistol was replaced by the Beretta M9 9mm pistol as the main sidearm of the U.S. military, although select Special Operations units continue to use the M1911A1 or other .45 ACP pistols.

Because standard pressure and load .45 ACP rounds fired from handguns or short barreled submachine gun
Submachine gun
A submachine gun is an automatic carbine, designed to fire pistol cartridges. It combines the automatic fire of a machine gun with the cartridge of a pistol. The submachine gun was invented during World War I , but the apex of its use was during World War II when millions of the weapon type were...

s are inherently subsonic, it is one of the most powerful pistol calibers available for use in suppressed weapons
Suppressor
A suppressor, sound suppressor, sound moderator, or silencer, is a device attached to or part of the barrel of a firearm which reduces the amount of noise and flash generated by firing the weapon....

 since subsonic rounds are quieter than supersonic rounds. The latter inevitably produce a highly compressed shock wave
Shock wave
A shock wave is a type of propagating disturbance. Like an ordinary wave, it carries energy and can propagate through a medium or in some cases in the absence of a material medium, through a field such as the electromagnetic field...

, audible as a loud "crack", literally a small sonic boom
Sonic boom
A sonic boom is the sound associated with the shock waves created by an object traveling through the air faster than the speed of sound. Sonic booms generate enormous amounts of sound energy, sounding much like an explosion...

, while they travel through the air. Suppressors reduce the audible "report" by slowing and channeling the high speed gas generated by the burning/expanding gunpowder before it exits the muzzle resulting in a muffled "cough". Suppressors cannot act on a supersonic shock wave continuously generated by a bullet exceeding the 1100 ft/s (335.3 m/s) speed of sound, as this shock wave is continuously produced throughout the entire flight path over which the bullet is supersonic, which extends long after it exits the barrel. The downside to the use of .45 ACP in suppressed weapons is that increasing the diameter of the passage through a suppressor decreases the suppressor's efficiency; thus, while .45 ACP is among the most powerful suppressed pistol rounds, it is also one of the loudest. Most .45 suppressors must be fired "wet" (with an ablative
Ablation
Ablation is removal of material from the surface of an object by vaporization, chipping, or other erosive processes. This occurs in spaceflight during ascent and atmospheric reentry, glaciology, medicine, and passive fire protection.-Spaceflight:...

 medium, usually water) to bring sound levels down to "hearing-safe" (under 140 dB, generally).

Load variants

Several manufacturers market preloaded .45 ACP rounds in sizes ranging from 117 to 250 grains (8 g to 16 g), with the most popular commercial load being the standard military loading of a 230-grain (15 g) FMJ bullet at around 850& ft/s (260 m/s). Specialty rounds are available in weights under 100 grains (6.5 g) and over 260 grains (16.8 g); popular rounds among reloaders and target shooters include 185-and 230-grain (12 g and 15 g) bullets. Hollow-point rounds intended for maximum effectiveness against live targets are designed to expand upon impact with soft tissue, increasing the size of the permanent cavity left by the bullet as it passes through the target.

Most ammunition manufacturers also market what are termed "+P" loadings in pistol ammunition, including the .45 ACP. This means the cartridge is loaded to a higher maximum pressure level than the original SAAMI
Sporting Arms and Ammunition Manufacturers' Institute
The Sporting Arms and Ammunition Manufacturers' Institute is an association of American firearms and ammunition manufacturers...

 cartridge standard, generating higher velocity and more muzzle energy. In the case of the 45 ACP, the standard cartridge pressure is 21,000 PSI and the SAAMI 45 ACP +P standard is 23,000 PSI. This is a common practice for updating older cartridges to match the better quality of materials and workmanship in modern firearms.

The terminology is generally given as ".45 ACP +P", and appears on the headstamp
Headstamp
A headstamp is the markings on the bottom of a cartridge case designed for a firearm. It usually tells who manufactured the case. If it is a civilian case it often also tells the caliber, if it is military, the year of manufacture is often added....

. It is important to note that +P cartridges have the same external dimensions as the standard-pressure cartridges and will chamber and fire in all firearms designed for the standard-pressure loadings. However, It should be noted that the inner dimensions of the +P cartridge are different than the standard-pressure cartridge dimensions and thus allows for higher pressures to be safely achieved in the +P cartridge. If +P loadings are used in firearms not specifically designed for them they may cause damage to the weapon and injuries to the operator.

Popular derivative versions of the .45 ACP are the .45 Super
.45 Super
The .45 Super is a smokeless powder center fire metallic firearm cartridge developed in 1988 by Dean Grennell, a well-known writer in the firearms field as well as managing editor of Gun World magazine...

 and .460 Rowland
.460 Rowland
The .460 Rowland is a proprietary cartridge intended to attain .44 Remington Magnum level velocities with a M1911-pattern semi-automatic pistol. The cartridge concept originated with Johnny Rowland, the host of "The Shooting Show"...

. The Super is dimensionally identical to the .45 ACP, however, the cartridge carries a developer established pressure of 28,500 PSI and requires minor modification of quality firearms for use. The Rowland case is 0.057" longer specifically to prevent it from being chambered in standard .45 ACP firearms. The Rowland operates at a developer established 40,000 c.u.p. and may only be used within a select group of firearms significantly modified for this purpose. Brass cases for each of these cartridges carry the applicable name within the headstamp. The Super provides approximately 20% greater velocity than the .45 ACP +P; the Rowland approximately 40% greater velocity than the .45 ACP +P.

Timeline

  • 1899/1900: Self-loading pistols test: Colt M1900
    Colt M1900
    The Colt Model 1900 was a self-loading semi-automatic .38 caliber handgun introduced by Colt at the turn of the 20th century. It also marked the introduction of .38 ACP, the round for which it is chambered ....

     of .38
    .38 ACP
    The .38 ACP also known as the .38 Auto was introduced at the turn of the 20th century for the Browning designed Colt M1900. The cartridge headspaces on the rim. It had first been used in his Model 1897 prototype, which Colt did not produce...

     caliber entered.
  • 1904: Thompson-LaGarde Tests
    Thompson-LaGarde Tests
    The Thompson-LaGarde Tests were a series of tests conducted in 1904 to determine which caliber should be used in new military handguns. The US Army's fighting men had considerable difficulty stopping the Moro warriors and other combatants with the .38 Long Colt, and the Army began to consider the...

    —caliber of new handgun should be at least .45.
  • 1906–1907: Handgun trials—Colt enters with .45 ACP design.
  • 1910: Final tests—Colt pistol (designed by John Browning) out-performs Savage.
  • March 29, 1911: The Colt pistol is officially adopted as the Model 1911—and with it, the .45 ACP cartridge.

Related rounds

  • .38/.45 Clerke
    .38/.45 Clerke
    The .38/45 Clerke aka .38/45 Auto Pistol or .45-38 Auto Pistol is an automatic pistol cartridge developed by Bo Clerke and introduced in Guns & Ammo in 1963.-History and Design:...


  • .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....

  • .45 G.A.P.
    .45 GAP
    The .45 G.A.P. pistol cartridge was designed by Ernest Durham, an engineer with CCI/Speer, at the request of firearms manufacturer Glock to provide a cartridge that would equal the power of the .45 ACP but was shorter to fit in a more compact handgun, and with a stronger case head to reduce the...

  • .45 Winchester Magnum
    .45 Winchester Magnum
    The .45 Winchester Magnum is a .45 caliber rimless cartridge intended for use in semi-automatic pistols. The cartridge is a stretched version of the .45 ACP with additional strengthening in the web area to accommodate the higher operating pressure...

  • .45 Peters
    Peters Cartridge Company
    The Peters Cartridge Company was a company in Kings Mills, Ohio that specialized in gunpowder and ammunition production. Its historic buildings, built in 1916 at 1915 Grandin Road, were added to the National Register of Historic Places on October 10, 1985....

    -Thompson shot cartridge
  • .50 GI
    .50 GI
    - External links :* *...

  • .45 Auto Rim
    .45 Auto Rim
    The .45 Auto Rim is a rimmed cartridge specifically designed to be fired in revolvers originally chambered for the .45 ACP cartridge. Remington-Peters developed the cartridge for use in the M1917 revolver, large amounts of which had become available as surplus following the end of the Great War...


External links

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