. 38 Special The . 38 Smith & Wesson Special ( commonly . 38 Special , . 38 Spl , or . 38 Spc , pronounced " thirty - eight special " ) is a rimmed , centerfire cartridge designed by Smith & Wesson . It is most commonly used in revolver s , although some semi - automatic pistols and carbine s also use this round . The . 38 Special was the standard service cartridge of most police departments in the United States from the 1920s to the early 1990s , and was also a common sidearm cartridge used by soldiers in World War I . In other parts of the world , it is known by its metric designation of 9×29 . 5mmR or 9 . 1x29mmR . Noted for its fine accuracy and manageable recoil , it remains the most popular revolver cartridge in the world more than a century after its introduction . It is used for target shooting , formal target competition , personal defense , and for hunting small game . Characteristics . Despite its name , the caliber of the . 38 Special cartridge is actually . 357 – . 358 inches ( 9 . 0678 mm ) , with the " . 38 " referring to the approximate diameter of the loaded brass case . This came about because the original . 38 - caliber cartridge , the . 38 Short Colt , was designed for use in converted . 36 - caliber cap - and - ball ( muzzleloading ) Navy revolvers , which had cylindrical firing chambers of approximately diameter , requiring heeled bullet s , the exposed portion of which was the same diameter as the cartridge case ( see the section on the . 38 Long Colt ) . Except for case length , the . 38 Special is identical to that of the . 38 Short Colt , . 38 Long Colt , and the . 357 Magnum . This allows the . 38 Special round to be safely fired in revolvers chambered for the . 357 Magnum , and the . 38 Long Colt to be fired in revolvers chambered for . 38 Special , and the . 38 Short Colt to fire in revolvers chambered for . 38 Long Colt , increasing the versatility of this cartridge . However , the longer and more powerful . 357 Magnum cartridge will usually not chamber and fire in weapons rated specifically for . 38 Special ( e . g . all versions of the Smith & Wesson Model 10 ) , which are not designed for the greatly increased pressure of the magnum rounds . Both . 38 Special and . 357 Magnum will chamber in Colt New Army revolvers in . 38 Long Colt , due to the straight walled chambers , but should not be done under any circumstances , due to dangerous pressure levels , up to three times what the New Army is designed for . History . The . 38 Special was introduced in 1898 as an improvement over the . 38 Long Colt which , as a military service cartridge , was found to have inadequate stopping power against the frenzied charges of Moro warriors during the Philippine - American War . Upon its introduction , the . 38 Special was originally loaded with black powder , but the cartridge ' s popularity caused manufacturers to offer smokeless powder loadings within a year of its introduction . During the late 1920s , and in response to demands for a more effective law enforcement version of the cartridge , a new standard - velocity loading for the . 38 Special was developed by Western Cartridge Company . This . 38 Special variant incorporated a round - nosed lead ' Lubaloy ' bullet , the " . 38 Super Police " . Remington - Peters also introduced a similar loading . Testing revealed that the longer , heavier . 38 - calibre bullet fired at low velocity tended to ' keyhole ' or tumble upon impact , providing more shock effect against unprotected personnel . At the same time , authorities in Great Britain , who had decided to adopt the . 38 caliber revolver as a replacement for their existing . 455 service cartridge , also tested the same bullet in the smaller . 38 S & W cartridge . This cartridge was called the . 38 S & W Super Police or the . 38 / 200 . Britain would later adopt the . 38 / 200 as its standard military handgun cartridge . In 1930 , Smith & Wesson introduced a large frame . 38 Special revolver with a 5 inch barrel and fixed sights intended for police use , the Smith & Wesson " . 38 / 44 Heavy Duty " . The following year , a new high - power loading called the " . 38 Special Hi - Speed " with a metal - tip bullet was developed for these revolvers in response to requests from law enforcement agencies for a handgun bullet that could penetrate auto bodies and body armor . That same year , Colt Firearms announced that their Colt Official Police would also handle ' high - speed ' . 38 Special loadings . The . 38 / 44 high - speed cartridge came in three bullet weights : , , with either coated lead or steel jacket , metal - piercing bullets . The media attention gathered by the . 38 / 44 and its ammunition eventually led Smith & Wesson to develop a completely new cartridge with a longer case length in 1934 — the . 357 Magnum . During World War II , some U . S . aircrew ( primarily Navy and Marine Corps ) were issued . 38 Special S & W Victory revolvers as sidearms in the event of a forced landing . In May 1943 , a new . 38 Special cartridge with a , full steel jacketed , copper flash - coated bullet meeting the requirements of the rules of land warfare was developed at Springfield Armory and adopted for the Smith & Wesson revolvers . The new military . 38 Special loading propelled its bullet at a standard from a revolver barrel . During the war , many U . S . naval and marine aircrew were also issued red - tipped . 38 Special tracer rounds using either a bullet for emergency signaling purposes . In 1956 , the U . S . Air Force adopted the " Cartridge , Caliber . 38 , Ball M41 " , a military variant of the . 38 Special cartridge designed to conform to the rules of land warfare . The original . 38 M41 ball cartridge used a 130 - grain full metal jacketed bullet , and was loaded to an average pressure of only , giving a muzzle velocity of approximately from a barrel . This ammunition was intended to prolong the life of S & W M12 and Colt Aircrewman revolvers equipped with aluminum cylinders and frames , which were prone to stress fractures when fired with standard . 38 ammunition . By 1961 , a slightly revised M41 . 38 cartridge specification known as the " Cartridge , Caliber . 38 Ball , Special , M41 " had been adopted for U . S . armed forces using . 38 Special caliber handguns . The new M41 " Special " cartridge used a 130 - grain FMJ bullet loaded to a maximum allowable pressure of for a velocity of approximately in a solid test barrel , and about from a revolver barrel . The M41 ball cartridge was first used in . 38 revolvers carried by USAF aircrew and Strategic Air Command security police , and by 1961 was in use by the U . S . Army for security police , dog handlers , and other personnel equipped with . 38 Special caliber revolvers . A variant of the standard M41 cartridge with a semi - pointed , unjacketed lead bullet was later adopted for CONUS ( Continental United States ) police and security personnel . At the same time , . 38 tracer cartridges were reintroduced by the US Navy , Marines , and Air Force to provide a means of emergency signaling by downed aircrew . Tracer cartridges in . 38 Special caliber of different colors were issued , generally as part of a standard aircrew survival vest kit . A request for more powerful . 38 Special ammunition for use by Air Police and security personnel resulted in the " Caliber . 38 Special , Ball , PGU - 12 / B High Velocity " cartridge . Issued only by the U . S . Air Force , the PGU - 12 / B had a greatly increased maximum allowable pressure rating of 20 , 000 psi , sufficient to propel a 130 - grain FMJ bullet at from a solid test barrel , and about 950 – 980 ft / s from a revolver barrel . The PGU - 12 / B " High Velocity " cartridge differs from M41 " Special " ammunition in two important respects — the " PGU - 12 / B " is a much higher - pressure cartridge , with a bullet deeply set and crimped into the cartridge case . In response to continued complaints over ineffectiveness of the standard . 38 Special 158 - grain cartridge in stopping assailants in numerous armed confrontations during the 1950s and 1960s , ammunition manufacturers began to experiment with higher - pressure ( 18 , 500 CUP ) loadings of the . 38 Special cartridge , known as . 38 Special + P . In 1972 , the Federal Bureau of Investigation introduced a new . 38 + P loading that became known as the " FBI Load " . The FBI Load combined a more powerful powder charge with an 158 - grain unjacketed soft lead semi - wadcutter hollow - point bullet designed to readily expand at typical . 38 Special velocities obtained in revolvers commonly used by law enforcement . The FBI Load proved very satisfactory in effectively stopping adversaries in numerous documented shootings using 2 - to 4 - inch barreled revolvers . The FBI Load was later adopted by the Chicago Police Department and numerous other law enforcement agencies . Demand for a . 38 cartridge with even greater performance for law enforcement led to the introduction of the + P + . 38 Special cartridge , first introduced by Federal and Winchester . Originally labeled " For Law Enforcement Only " , + P + ammunition is intended for heavier - duty . 38 Special and . 357 Magnum revolvers , as the increased pressure levels can result in accelerated wear and significant damage to firearms rated for lower - pressure . 38 Special loadings ( as with other . 38 Special loadings , the . 38 Special + P + can also be fired safely in . 357 revolvers ) . Performance . Due to its black powder heritage , the . 38 Special is a low pressure cartridge , one of the lowest in common use today at 17 , 000 PSI . By modern standards , the . 38 Special fires a medium - sized bullet at rather low speeds . The closest comparisons are the . 380 ACP , which fires much lighter bullets slightly faster than most . 38 Special loads ; the 9×19mm Parabellum , which fires a somewhat lighter bullet significantly faster ; and the . 38 Colt Super , which fires a comparable bullet significantly faster . All three of these are usually found in semi - automatic pistols . The higher - pressure . 38 + P loads at 20 , 000 PSI offer about 20 % more muzzle energy than standard - pressure loads and places between the . 380 ACP and the 9 mm Parabellum ; similar to that of the 9×18mm Makarov . A few specialty manufacturers ' + P loads for this cartridge can attain even higher energies that , especially when fired from longer barrels , produce energies in the range of the 9mm Parabellum . It should be noted these loads are generally not recommend for older revolvers or ones not specifically " + P " rated . It is important to recognize that SAAMI changed the specifications for the . 38 Special in 1972 . Prior to that time the standard . 38 Special was very close to today ' s " + P " cartridges . All of the above specifications for . 38 loadings , and the . 357 Magnum , are applicable when fired from a barreled revolver . The velocity is reduced when using the more standard barreled guns . Power ( muzzle energy ) will , of course , decrease accordingly . Although few , if any US police departments now issue or authorize use of the . 38 Special revolver as a standard duty weapon , the caliber remains popular with some police officers for use in short - barreled revolvers carried when off - duty or for undercover police investigations . It is also widely used in revolvers purchased for civilian home defense or for concealed carry by individuals with a CCW permit . Terminal performance and expansion . There are many companies that manufacture . 38 Special ammunition . It can range from light target loads to more powerful defensive ammunition . Because of the relatively low pressure that the . 38 Special cartridge and even its more powerful + P version can be loaded to , most . 38 Special bullets do not expand reliably , even when using hollow - point designs , especially if fired from a short - barreled or ' snub - nose ' revolver . In 2004 , Speer Bullets introduced the " Gold Dot " jacketed hollow - point . 38 Special cartridge in an attempt to solve this very problem . Another solution is to use an unjacketed soft lead hollow - point bullet as found in the " FBI Load " . The latter ' s 158 - grain soft lead hollow point is loaded to + P pressures and velocity , which ensures more reliable expansion in unprotected flesh , even when fired in a 2 - inch short - barreled revolver . Handloading . The . 38 Special is particularly popular among handloaders . The cartridge ' s straight walls , headspacing on the rim , ready availability of previously - fired cases , and ability to be fired in . 357 Magnum firearms , all contribute to this popularity . Additionally , the . 38 Special ' s heritage as a black powder cartridge gives it a case size capable of accommodating many types of powders , from slower - burning ( e . g . Hodgdon H - 110 or Hercules 2400 ) to fast - burning ( e . g . Alliant Bullseye , the traditional smokeless powder for this cartridge ) . This flexibility in powders translates directly to versatility in muzzle energy that a handloader can achieve . Thus , with proper care , a suitably - strong revolver , and adherence to safe handloading practices , the . 38 Special can accommodate ammunition ranging from light - recoiling target loads to + P + self - defense rounds .