.45 ACP: Difference between revisions

|case_capacity=26 25 - 27.74

|primer= Large pistol LP (some makers are now using small) pistol SP)

The '''.45 ACP''' ([[Automatic Colt Pistol]]), oralso known as '''.45 Auto''', ('''.45 Automatic''', or '''11.43×23mm)'''<ref>{{Cite book |title=Handbook of Handguns |last=Strickland |first=Jeffrey |page=151 |date=2014 |publisher=LULU.COM |isbn=978-1-300973294 |location=[S.l.]|oclc=1020871429}}</ref> is a [[Rim (firearms)#Rimless|rimless]] straight-walled handgun [[Cartridge (firearms)|cartridge]] designed by [[John Moses Browning]] in 1904, for use in his prototype [[Colt's Manufacturing Company|Colt]] [[semi-automatic pistol]]. After successful military trials, it was adopted as the standard chambering for Colt's [[M1911 pistol]].<ref name="COTW14">{{cite book |last1=Barnes |first1=Fred C. |title=Cartridges of the World |date=2014 |publisher=Krause Publications |location=Iola, WI |isbn=978-1-4402-4265-6}}</ref> The round was developed due to a lack of stopping power experienced<ref>{{Cite web |last=Tong |first=David |date=2020-11-07 |title=History of the .45 ACP Cartridge |url=https://www.ammoland.com/2020/11/history-45-acp-cartridge/ |access-date=2021-06-17 |website=AmmoLand.com |language=en-US}}</ref> in the [[Moro Rebellion]] in places like [[Sulu]]. The issued ammunition, [[.38 Long Colt]], had proved inadequate, motivating the search for a better cartridge. This experience and the [[Thompson–LaGarde Tests]] of 1904 led the Army and the Cavalry to decide that a minimum of .45 caliber was required in a new handgun cartridge.

The standard -issue military .45 ACP round uses a {{convert|230-[[Grain (unit)|grain]] (14.9 gr|g) roundoz|abbr=on|lk=on}} round-nose projectile that travelsbullet at approximately {{convert|830 feet per second (250 |ft/s|m/s) when|abbr=on}} fired from a government-issue M1911A1 pistol. It operates at a relatively low maximum [[chamber pressure]] rating of {{Cvt|21000|psi|MPa|lk=on}}, compared to {{Cvt|35000|psi|MPa|lk=on}} for both [[9×19mm Parabellum|9mm Parabellum]] and [[.40 S&W]], which due to a low [[bolt thrust]] helps extend the service lives of weapons. Since standard-pressure .45 ACP rounds are subsonic when fired from [[handgun]]s and [[submachine gun]]s, it is a useful caliber for [[silencer (firearms)|suppressed]] weapons to eliminate the [[sonic boom]].

[[File:.45 ACP U.S. Army ball cartridge diagram.jpg|thumb|left|Cross-sectional diagram of U.S. Army .45 ACP " ball cartridge" for the Model 1911 pistol, with dimensions in inches]]

During the late 19th century and early 20th centuries, the [[United States Cavalry|U.S. Cavalry]] began trials to replace their sidearm arsenal of issued [[.45 Colt]] [[Colt Single Action Army|Single Action Army]] (SAA) in favor of the more modern and versatile [[Revolver#Double-action|double-action revolver]] in [[.45 Colt]].

After the example of the Cavalry, the Army in turn had fielded versions of [[Revolver#Double-action|double-action revolvers]] in [[.38 Long Colt]]. It was eventually evaluated that the .38 caliber round was significantly less effective in overall stopping power than the [[.45 Colt]] against determined opponents in cases such as the Tausug [[Moro people|Moro]] [[juramentado]] warriors, who were encountered in the [[Moro Rebellion]].<ref name="DK2006">{{cite book |author=DK |title=Weapon: A Visual History of Arms and Armor |url=https://books.google.com/books?id=Px5E3EIF5jQC&pg=PA290 |date=2 October 2006 |publisher=[[DK (publisher)|DK Publishing]] |isbn=978-0-7566-4219-8 |page=290 |access-date=August 26, 2016 |archive-url=https://web.archive.org/web/20170322080306/https://books.google.com/books?id=Px5E3EIF5jQC&pg=PA290 |archive-date=March 22, 2017 |url-status=live}}</ref><ref name="The2008">{{cite book |author=The Green Muse Writers Collective |title=Keep Calm Carry on: A Survival Guide |url=https://books.google.com/books?id=auxpWQox1j8C&pg=PA138 |date=December 2008 |publisher=iUniverse |isbn=978-1-4401-0249-3|page=138}}</ref><ref>{{cite web |url=http://www.manilatimes.net/juramentados-and-the-development-of-the-colt-45-caliber-model-1911/107609/ |title=Juramentados and the development of the Colt .45 caliber Model 1911 |website=[[The Manila Times]] Online |date=2014-06-29 |access-date=August 26, 2016 |archive-url=https://web.archive.org/web/20160915083326/http://www.manilatimes.net/juramentados-and-the-development-of-the-colt-45-caliber-model-1911/107609/ |archive-date=September 15, 2016 |url-status=live}}</ref><ref>{{Cite journal |url=http://www.bagongkasaysayan.org/saliksik/wp-content/uploads/2014/11/13-Artikulo-Lasco.pdf |title=Ang "Kalibre 45" At Ang Pakikibaka Ng Mga Mandirigmang Pilipino |trans-title=The "Kaliber 45" and The Struggle of the Filipino Warriors |language=fil |first=Lorenz |last=Lasco |date=November 2014 |journal=Saliksik |volume=3 |number=2 |pages=275–306 |access-date=January 8, 2018 |archive-url=https://web.archive.org/web/20161009151138/http://www.bagongkasaysayan.org/saliksik/wp-content/uploads/2014/11/13-Artikulo-Lasco.pdf |archive-date=October 9, 2016 |url-status=dead}}</ref> The standard-issue rifle, the [[.30-40 Krag]], had also failed to stop Moro warriors effectively;<ref>{{cite web |url=http://www.sightm1911.com/1911%20History.htm |title=History of the M1911 Pistol |website=Sight M1911 |url-status=dead |archive-url=https://web.archive.org/web/20060716083501/http://www.sightm1911.com/1911%20History.htm |archive-date=July 16, 2006}}</ref> the British had similar lack-of-stopping-power issues switching to the [[.303 British]], which resulted in the development of the ''[[Expanding bullet|dum-dum]]'' bullet, in an attempt to compensate for the round's deficiencies. This experience, and the [[Thompson–LaGarde Tests]] of 1904, led the Army and the Cavalry to decide a minimum of .45 caliber was required in a new handgun. Thompson and Major [[Louis La Garde|Louis Anatole La Garde]] of the medical corps arranged tests on cadavers and animals in the Chicago stockyards, resulting in their declaring that the .45 was the most effective pistol cartridge. They noted, however, training was critical to make sure a soldier could score a hit in a vulnerable part of the body.

By 1906, bids from six makers were submitted, among them, Browning's design, submitted by Colt. Only [[Deutsche Waffen und Munitionsfabriken|DWM]], [[Savage Arms|Savage]], and Colt made the first cut. DWM, which submitted two [[Luger pistol|Parabellum]]s chambered in .45 ACP, withdrew from testing after the first round of tests, for unspecified reasons.<ref name="back">{{cite web |url=http://www.sightm1911.com/lib/history/background.htm |title=Background Information on the M1911 .45 Caliber Pistol |first=David L. |last=Velleux |website=Sight M1911 |access-date=May 16, 2007 |archive-url=https://web.archive.org/web/20070514053639/http://www.sightm1911.com/lib/history/background.htm |archive-date=May 14, 2007 |url-status=live}}</ref>

InDuring the second round of evaluations in 1910, the Colt design passed extensive testing with no failures, while the Savage design suffered 37 stoppages or parts failures.<ref name="back"/> The Colt pistol was adopted as the [[M1911 pistol|Model 1911]].

[[File:Caliber .45 Ball M1911.jpg|thumb|45 x 2311.43x23 mm Automatic Colt Pistol Mod. 1911 (Peters Cartridge Co, USA)]]

It came in either 24-round revolver ammo cartons, containing eight 3-round "half-moon" clips (1917-1945), pre-war 20-round cartons (1911-1942), or wartime 50-round cartons (1942–present). The M12 and M15 shotshell rounds were packed in 20-round cartons sealed in heat-sealed foil-lined Kraft paper.

:''Caliber .45 shot M12(T23)'' (1943-1944 ) was a survival round with a round-nosed red [[wax paper]] projectile containing 118 pieces of No . 7 {{frac|1|2}} birdshot. It was issued in USAAF survival kits<ref group="note">The ammunition was packed in USAAF B-2 and B-4 emergency kits and C-1 survival vests.</ref> to allow pilots and aircrew armed with the Colt M1911A1 to use it for hunting small game.<ref group="note">The trials cartons originally had the instructions "Use only for hunting game. Do not use against enemy troops" in both English and either German or Japanese on the front. This was later changed to "For use in hunting small game, effective range {{convert|25 feet|ft|m|disp=sqbr}}" and the foreign language text was dropped.</ref> The shotshell was a little longer than a standard round, so the operator had to load it in the action individually.<ref group="note">Text on the instructions slip packed with the ammunition carton (the last sentence is from the reverse side of the slip): "Instructions: This cartridge is intended for killing small game. Because of {{notatypoas written|i|t's [sic]|it's a typo}} length it will not feed in magazines, and each round must be loaded by hand. To load in the automatic pistol, draw slide back and lock in rearward position. Insert cartridge in chamber. [Depress slide stop, allowing slide to move forward.]"</ref> It was extracted after firing by removing the magazine, pulling back the slide, and pushing down on the case until it fell down the magazine well.<ref group="note">Text on the reverse of the instructions slip packed with the ammunition carton: "Instructions [...] If it be necessary, to remove an unfired cartridge from pistol, remove magazine, draw slide back and push downward on cartridge, allowing it to fall out through magazine slot."</ref> Reports showed that the paper projectile was affected by humidity and would swell or break apart. It was made limited standard until replaced by the .45 M15 shot cartridge.

:''Cartridge, S.A., .45-inch, ball Mk Iz'' (1940–1945) was the designation used for American-manufactured ammunition and proposed British manufacture of .45 M1911 ball. Lend-lease ammunition came in commercial 42-round yellow Winchester or 50-round white Western Cartridge Company cartons. U.S. military-issue ammunition came in 20-round cartons, shifting to larger 50-round cartons in early 1942. It was never manufactured in Britain because it was readily available from American forces.

:''Cartouche de 11,443 3mmmm, Pour Pistolets'' ('11.43 mm cartridge for pistols'): ''Balle ordinaire'' ('ordinary ball') pistol ammunition. Post-war production for use in the pistols and submachineguns given out by the US as military aid. It came in 25-round cartons.

The .45 ACP has 1.62 mL ({{convert|25 [[Grain (unit)|–|27.4|gr|g]]|lk=in}} H₂O)of {{H2O-nl}} cartridge case capacity, depending on manufacturer and production lot.

The .45 ACP is an effective combat pistol cartridge. It combines accuracy as well as stopping power for use against human targets, has relatively low muzzle blast and flash, and it produces a stout, but manageablemoderate [[recoil]] in handguns (made worse in compact models).

The .45 ACP is generally considered to have a highergreater stopping power asthan compared tothe 9mm.{{cncitation needed|date=July 2023}} Due to its larger size and slower velocity it creates a larger wound channel and transfers more energy to the target.

The standard-issue, military .45 ACP cartridge contains a {{convert|230-grain|gr|g|adj=on}} bullet that travels at approximately {{Convert|830|ft/s|0|abbr=out}} when fired from the government-issue M1911A1 pistol, and approximately {{Convert|950|ft/s|0|abbr=out}} fired from the [[Thompson submachine gun|Thompson M1A1 submachine gun]]. The cartridge comes in various specialty rounds of varying weights and performance levels as well.<ref name="COTW14"/>

The cartridge operates at a relatively low maximum [[chamber pressure]] rating of {{Cvt|21000|psi|MPa|0}} (compared to {{Cvt|35000|psi|MPa|0|disp=sqbr}} for [[9×19mm Parabellum|9mm Parabellum]] and [[.40 S&W]], {{Cvt|37500|psi|MPa|0|disp=sqbr}} for [[10mm Auto]], {{Cvt|40000|psi|MPa|0|disp=sqbr}} for [[.357 SIG]]), which due to a low [[bolt thrust]] helps extend service life of weapons in which it is used. Some makers of pistols chambered in .45 ACP, do not certify them to use Plus +P ammunition.

In its expanding [[jacketed hollow point|hollow point]] form, it is also particularly effective against human targets. In tests against ballistic gelatin, a {{convert|185-grain|gr|g|adj=on}} hollow point traveling at {{convert|1,050 feet per second|ft/s|m/s}} expanded to about {{convert|.76 inch|in|mm}}. This is a significantly large permanent wound cavity for a handgun projectile. For those who follow the energy dump and/or hydrostatic shock theories of wounding ballistics, this is ideal. While slightly decreasing penetration and likewise the chance of hitting a vital organ, a large diameter wound will cause more blood loss. There is also a reduced likelihood of overpenetration, meaning that it is more likely that the projectile will transfer all of its kinetic energy to the intended target, thus more reliably incapacitating them.

Drawbacks for military use include the cartridge's large size, weight, and increased material costs in comparison to the smaller, flatter shooting [[NATO]] standard 9×19mm Parabellum cartridge, a cartridge which uses less powder, brass, and lead per round. Standard 9mm NATO ammunition has a more limited armor penetration capability—a deficiency shared with .45 ACP, whose large, slow bullet does not penetrate armor to any great extent. The low muzzle velocity also makes the bullet drop more over long ranges, making hits more difficult; however, it is important to note that the vast majority of self-defense situations involving handguns typically occur at close ranges.

After two years of testing, one of the final FBI comments was that services that adopt (or stay with) .40 S&W or .45 ACP, did so at the risk of increased recoil and a possible reduction in accuracy as 9×19mm with premium quality ammunition had nearly exactly the same performance.<ref name="Grandview-FBI 9mm">{{cite web |title=Case Closed: FBI Says 9mm Is The Best Pistol Round |url=http://www.grandviewoutdoors.com/guns/case-closed-fbi-says-9mm-is-the-best-pistol-round/ |first=Christian |last=Lowe |date=September 26, 2014 |website=Grand View Outdoors |access-date=23 February 2017 |quote=There is little to no noticeable difference in the wound tracks between premium line law Auto enforcement projectiles from 9mm Luger through the .45 Auto. |archive-url=https://web.archive.org/web/20170215232656/http://www.grandviewoutdoors.com/guns/case-closed-fbi-says-9mm-is-the-best-pistol-round/ |archive-date=February 15, 2017 |url-status=live}}</ref> A factor rated by the recent FBI testing was accuracy and time to recover. The .45 ACP handguns ranked last, largely due to increased recoil.<ref name="Grandview-FBI 9mm"/>

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 ACP suppressors must be fired "wet" (with an [[Ablation|ablative]] medium, usually oil or water) to bring sound levels down to "hearing-safe" (under 140&nbsp;[[Decibel|dB]], generally).<ref name="SSA">{{cite book |last=Truby |first=J. David |date=1987 |title=Silencers, Snipers, and Assassins...an Overview of Whispering Death |location=Boulder, Colorado |publisher=Paladin Press |page=216 |isbn=0-87364-012-8}}</ref>

Magazine capacity varies depending on the type of firearm. Standard (not extended) single-stack magazines for pistols based on the 1911 design commonly, hold eight rounds or fewer in .45 ACP. Many modern pistols have adapted the cartridge into double-stacked magazine designs to increase ammo capacity, though this increases the pistol grip's handle girth, but not width. The less-rounded back strap helps to spread the recoil out more and make the pistol more pleasant to shoot. [[Drum magazine]]s used mostly for submachine guns have a capacity of 50 or 100 rounds.

Several US tactical police units still use the .45 pistol round.<ref name="SPTF">{{cite book |title=Special Police Task Forces |last=Diez |first=Octavio |year=2000 |page=40 |publisher=Lima Publications |isbn=978-84-95323-43-9}}</ref><ref name="janes">{{cite book |title=Jane's Gun Recognition Guide |edition=2nd |editor-last=Hogg |editor-first=Ian |page=113 |date=2000 |publisher=Harper Collins Publishers}}</ref><ref name="AmeHand">{{Cite magazine |url=http://www.findarticles.com/p/articles/mi_m0BTT/is_144_24/ai_57886947 |title=Most Wanted |last=Hopkins |first=Cameron |date=January 2000 |magazine=[[American Handgunner]] |access-date=February 21, 2007 |archive-url=https://web.archive.org/web/20041209014701/http://www.findarticles.com/p/articles/mi_m0BTT/is_144_24/ai_57886947 |archive-date=December 9, 2004 |url-status=dead}}</ref> 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, such as 9×19mm Parabellum; 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]].<ref name="COTW">{{cite book |last1=Barnes |first1=Frank C. |last2=Skinner |first2=Stan |title=Cartridges of the World |edition=10th Revised & Expanded |publisher=Krause Publications |year=2003 |page=528 |isbn=978-0-87349-605-6}}</ref> In addition, select military and police units around the world still use firearms firing the .45 ACP.<ref name="COTW"/> 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 [[M1911 pistol|M1911A1]] or other .45 ACP pistols.

Rounds are available from {{convert|68 grains |to |300 grains (4.4 |gr|g to 19 g)|adj=on}} with a common load being the standard military loading of a {{convert|230|gr||adj=on}} FMJ bullet (for comparison, the most common [[9×19mm Parabellum|9mm]] load is {{convert|115|gr|}}, half the weight). Specialty rounds are available in weights under {{convert|100|gr|}} and over {{convert|260|gr|}}; popular rounds among reloaders and target shooters include {{convert|185-grain |to |230-grain (12 |gr|g to 15 g)|adj=on}} bullets.<ref>{{Cite web |url=http://www.bullseyepistol.com/reloads.htm |title=Reloading Data for Pistol Competition |first=John |last=Dreyer |website=Encyclopedia of Bullseye Pistol |access-date=2022-12-19}}</ref><ref>{{Cite web |url=https://stevespages.com/451p_1.html |title=451p_1 |website=Stevespages.com |access-date=2022-12-19 |url-access=subscription}}</ref> Target shooters competing in Bullseye Pistol (aka [[NRA Precision Pistol|Precision Pistol]]) find that .45 ACP ammunition using light bullets (12 to 13 g) and low velocities paradoxically generates less recoil than 9mm ammunition of equivalent accuracy, despite its larger caliber, and allows better scores in sustained fire. 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.

Popular derivative versions of the .45 ACP are [[.45 Super]] and [[.460 Rowland]].<ref name="COTW"/> The Super is dimensionally identical to the .45 ACP; however, the cartridge carries a developer established pressure of {{cvt|28500|psi|MPa|0}} and requires minor modification of firearms for use. The Rowland operates at a developer established {{cvt|40000|psi|MPa|0}} [[SAAMI]] and may only be used within a select group of firearms significantly modified for this purpose; the Rowland case is {{convert|0.057|in|0}} longer specifically to prevent it from being chambered in standard .45 ACP firearms. 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.<ref name="COTW"/>

*11,.43 (Mexico, [[Obregón pistol]])

*11&nbsp;mm (Southeast Asia)<ref>{{cite news |url=https://www.bangkokpost.com/news/crime/1446430/man-shot-injured-by-fugitive-gunman |title=Fugitive gunman shoots drug-taking relative |work=[[Bangkok Post]] |archive-url=https://archive.phtoday/bW6nf20221123154733/https://www.bangkokpost.com/thailand/general/1446430/man-shot-injured-by-fugitive-gunman |archive-date=23 November 2022 |date=15 April 2018 |last=Rakrun |first=Nujaree}}</ref><ref>{{cite news |url=https://www.bangkokpost.com/thailand/general/299523/cheap-handgun-scheme-misfires |title=Cheap handgun scheme misfires |work=Bangkok Post |archive-url=https://archive.phtoday/oaEY420221123151054/https://www.bangkokpost.com/thailand/general/299523/cheap-handgun-scheme-misfires |archive-date=23 November 2022 |first=Wassayos |last=Ngamkham |date=25 June 2012}}</ref><ref>{{cite web |url=http://soha.vn/sung-ngan-ma-vang-thiet-ke-rieng-cho-tong-thong-my-donald-trump-20180121082708095.htm |title=Súng ngắn mạ vàng thiết kế riêng cho Tổng thống Mỹ Donald Trump |trans-title=Gold-plated pistol designed specifically for US President Donald Trump |language=vi |date=21 January 2018 |website=VCCorp.vn |access-date=April 15, 2018 |archive-url=https://web.archive.org/web/20180416073344/http://soha.vn/sung-ngan-ma-vang-thiet-ke-rieng-cho-tong-thong-my-donald-trump-20180121082708095.htm |archive-date=April 16, 2018 |url-status=live}}</ref>