View source for .38 ACP

{{short description|Pistol cartridge designed by John Moses Browning}}
{{distinguish|.380 ACP}}
{{Infobox firearm cartridge
| name = .38 ACP
| image = 38 ACP.jpg | image_size = 150px
| caption = 
| origin = United States
| type = Pistol
<!-- Service history -->
| service = 
| used_by = 
| wars = 
<!-- Production history -->
| designer = [[John Browning]]
| design_date = 1900
| manufacturer = [[Colt's Manufacturing Company|Colt]]
| production_date = 1900–present
| number = 
| variants = [[.38 Super]]
<!-- Specifications -->
| is_SI_specs = 
| parent = 
| case_type = Semi-rimmed, straight
| bullet = .356
| land = .346
| neck = .384
| shoulder = 
| base = .384
| rim_dia = .406
| rim_thick = .050
| case_length = .900
| length = 1.28
| rifling = 
| primer = Small pistol
|max_pressure= 26500
<!-- Ballistic performance -->
| is_SI_ballistics = 
| bw1 = 115
| btype1 = FMJ
| vel1 = 1150
| en1 = 338
| bw2 = 125
| btype2 = JHP
| vel2 = 1100
| en2 = 336
| bw3 = 130
| btype3 = FMJ
| vel3 = 1040
| en3 = 312
| bw4 = 
| btype4 = 
| vel4 = 
| en4 = 
| test_barrel_length = 
| balsrc = ''Cartridges of the World''<ref name="cotw">{{cite book  | last = Barnes  | first = Frank C.  | editor-last = Skinner | editor-first = Stan  | title = Cartridges of the World  | edition = 11th  | orig-year = 1965  | year = 2006  | publisher = Gun Digest Books  | location = Iola, Wisconsin, USA  | pages =328, 338  | isbn = 0-89689-297-2}}</ref>
}}

The '''.38 ACP''' ([[Automatic Colt Pistol]]), also known as the '''.38 Auto''', '''.38 Automatic''', or '''9×23mmSR''', is a [[Rim (firearms)#Semi-rimmed|semi-rimmed]] [[pistol]] [[cartridge (firearms)|cartridge]] that was introduced at the turn of the 20th century for the [[John Browning]]-designed [[Colt M1900]]. It was first used in Colt's Model 1897 prototype, which he did not produce. The metric designation for the round is 9×23mm SR (semi-rimmed), which is not to be confused with other [[9×23mm (disambiguation)|9×23mm]] cartridges, such as [[9×23mm Largo]] and [[9×23mm Steyr]].

==History==
Initial loadings of this cartridge were quite powerful. Reported ballistics for the first commercial loads were a 130-grain bullet at {{convert|1260|ft/s|m/s|abbr=on}}, and some experimental loads ran as high as {{convert|1350|ft/s|m/s|abbr=on}}.<ref name="SaF">Article in the April 19, 1900, issue of ''Shooting and Fishing,'' quoted in Belden, C. T. and Haven, ''A History of the Colt Revolver'' (1940)</ref> However, these ballistics proved too violent for the Colt Model 1900 pistol, and velocities were soon lowered to below {{convert|1200|ft/s|m/s|abbr=on}}. Subsequent commercial loadings varied considerably in power. For example, Hugh B. C. Pollard, writing in ''Automatic Pistols'' in 1920, gives Winchester factory ballistics for a 130-grain bullet at {{convert|1175|ft/s|m/s|abbr=on}} [[muzzle velocity]] and {{convert|398|ft.lbf|J|adj=on}} of muzzle energy; for Ely ammo, the figures for a 128-grain bullet were {{convert|1100|ft/s|m/s|abbr=on}} and {{convert|344|ft.lbf|J|adj=on}}; and for Kynoch a 130-grain bullet {{convert|1000|ft/s|m/s|abbr=on}}. Later U.S. commercial loads in this caliber had factory standard ballistics of a 130-grain bullet at {{convert|1040|ft/s|m/s|abbr=on}} from the {{convert|4.5|in|mm|adj=on}} barrel of the Colt 1903 Pocket Model.<ref name="Sapp 2007">
{{cite book
 | last = Sapp
 | first = Rick
 | title = Standard Catalog of Colt Firearms
 | year = 2007
 | publisher = F+W Media
 | location = Iola, Wisconsin
 | isbn = 978-0-89689-534-8
 | pages = 130–131
}}
</ref>
With the [[United States Army Ordnance Corps]] favoring a return to a .45 caliber sidearm by the time the Colt autos in .38 ACP were introduced, the caliber never gained much popularity. However, they did see small but steady sales up until the introduction of the more powerful [[.38 Super]], which was little more than the .38 ACP loaded back to its original ballistics.

Sales of .38 ACP ammunition enjoyed a modest spike during the surplus gun boom of the 1950s, 1960s, and 1970s; since the cartridges would usually cycle in Spanish surplus pistols like the [[Astra 400]] that were chambered for the [[9×23mm Largo]], even though the .38 ACP was semi-rimmed and slightly shorter than the rimless 9mm Largo. Some Astra 400 pistols were stamped "9M/M&38" on the barrel, denoting that the barrel was specifically designed to chamber both 9mm Largo and .38 ACP.<ref name="Sapp 2007"/>

Europe would eventually favor the [[9×19mm Parabellum]] cartridge. This cartridge is ballistically similar to the .38 ACP but utilizes a smaller case and higher pressures.

Browning himself was not done with 9 mm cartridges and introduced the [[9mm Browning Long]] in 1903 and the [[.380 ACP]] in 1908.

==.38 Super==
{{Main|.38 Super}}
.38 Super was introduced in 1929, as a higher pressure loading of the .38 ACP. Even though .38 ACP and .38 Super are the same size, it is dangerous to use the more powerful .38 Super ammunition in a firearm intended for .38 ACP, as firearm damage may result. In the interest of safety, American ammunition companies formerly loaded .38 Super ammunition in [[nickel]]ed cases exclusively. Since 1974, .38 Super cartridges have been marked with the [[Overpressure ammunition|+P]] markings used for greater pressure loads.

==Firearms chambered for .38 ACP==
Notable firearms chambered for this cartridge include:
{{div col}}
* [[Colt M1900]]
* [[Colt M1902]]
* [[Colt M1903 Pocket Hammer]]
* [[Webley-Fosbery Automatic Revolver]]
* [[Webley & Scott#Webley .26 Scott automatic pistols|Webley Automatic Pistol]]
* [[M1911 pistol]] (civilian market)
{{div col end}}

==See also==
* [[List of handgun cartridges]]

==References==
<references/>

==External links==
* [http://www.chuckhawks.com/subscribers/handgun_cartridge_page/38super.htm "The .38 Super Auto and .38 Auto (.38 ACP)"] by Chuck Hawks {{subscription required}}

{{John Browning}}
{{.38 Calibre}}
{{Colt's Manufacturing Company}}

{{DEFAULTSORT:38 ACP}}
[[Category:.38 ACP firearms| ]]
[[Category:Pistol and rifle cartridges]]
[[Category:Military cartridges]]
[[Category:Colt cartridges]]
[[Category:Weapons and ammunition introduced in 1900]]