. 357 Magnum The . 357 S & W Magnum ( 9x33mmR ) , or simply . 357 Magnum , is a revolver cartridge created by Elmer Keith , Phillip B . Sharpe , and Colonel D . B . Wesson of firearm s manufacturer Smith & Wesson , and Winchester . It is based upon Smith & Wesson ' s earlier . 38 Special cartridge . The . 357 Magnum cartridge was introduced in 1934 , and its use has since become widespread . This cartridge started the " Magnum " era of handgun ammunition . The . 357 Magnum cartridge has a positive reputation for stopping power . Design . The . 357 Magnum was collaboratively developed over a period in the early to mid - 1930s by a group of individuals in a direct response to Colt ' s . 38 Super Automatic . At the time , the . 38 Super was the only American pistol cartridge capable of defeating automobile cover and the early ballistic vest s that were just beginning to emerge in the post - World War I " Gangster Era . " Tests at the time revealed that those vests defeated any handgun cartridge traveling at less than about . Colt ' s . 38 Super Automatic just edged over that velocity and was able to penetrate car doors and vests that bootleggers and gangsters were employing as cover . Though . 38 and . 357 would seem to be different diameter chamberings , they are in fact identical . 0 . 357 inch is the true bullet diameter of the . 38 Special cartridge . The . 38 Special nomenclature relates to the previous use of heeled bullet s ( such as the . 38 Short Colt ) , which were the same diameter as the case . Thus , the only external difference in the two cartridges is a slight difference in length , solely for safety purposes as explained below . Much credit for the . 357 ' s early development is given to hunter and experimenter Elmer Keith . Keith ' s early work in loading the . 38 Special to increasingly higher pressure levels was made possible by the availability of heavy , target shooting - oriented revolvers like the Smith & Wesson . 38 - 44 " Heavy Duty " and " Outdoorsman " , . 38 - caliber revolvers built on . 44 - caliber frames . The . 38 - 44 HV load used the . 38 Special cartridge loaded to a much higher velocity than standard . 38 Special ammunition . The . 38 - 44 revolvers were made by using a . 44 Special size gun with the barrel and cylinder bored to . 357 caliber ( the true bullet diameter of the . 38 Special ) . Since the frame , cylinder , and barrel were much stronger than the standard . 38 Special components , it was capable of withstanding much higher pressures . The . 38 - 44 HV round , while no longer available , was in most cases the equal of the later . 357 Magnum , which works at more than double the pressure of standard . 38 Special . The . 357 Magnum addresses the safety issues earlier cartridges had by stretching the case by approximately , preventing the high pressure . 357 cartridge from chambering in a firearm designed for the shorter , lower pressure . 38 . Elmer Keith also contributed the Keith - style bullet , which increased the mass of bullet located outside of the cartridge , while leaving more room inside the cartridge for powder . The Keith bullet also employed a large , flat meplat , thus enabling rapid energy transfer for greater wounding properties . At the same time , this bullet design does not deform like a hollow point , and as a result achieves greater penetration . These characteristics of the Keith bullet make it very suitable for hunting applications as well as target shooting . In order to reassert itself as the leading law enforcement armament provider , Smith & Wesson developed the . 357 Magnum , with Colonel D . B . Wesson leading the effort within Smith & Wesson , along with considerable technical assistance from Phillip B . Sharpe , a member of the Technical Division Staff of the National Rifle Association . The new round was developed from Smith & Wesson ' s existing . 38 Special round . It used a different powder load , and ultimately the case was extended by . The case extension was more a matter of safety than of necessity . Because the . 38 Special and the early experimental . 357 Magnum cartridges loaded by Keith were identical in physical attributes , it was possible to load an experimental . 357 Magnum cartridge in a . 38 Special revolver , with potentially disastrous results . Smith & Wesson ' s solution , of extending the case slightly , made it impossible to chamber the magnum - power round in a gun not designed for the additional pressure . However , both . 38 Special and . 357 Magnum will chamber in Colt New Army revolvers in . 38 Long Colt , due to the straight walled chambers , but this should not be done under any circumstances , due to dangerous pressure levels , up to three times what the New Army is designed for . The choice of bullet for the . 357 Magnum cartridge varied during its development . During the development at Smith & Wesson , the original Keith bullet was modified slightly , to the form of the Sharpe bullet , which itself was based upon the Keith bullet , but which had 5 / 6 of the bearing surface of the Keith bullet , Keith bullets typically being made oversized and sized down . Winchester , however , upon experimenting further during the cartridge development , modified the Sharpe bullet shape slightly , while keeping the Sharpe contour of the bullet . The final choice of bullet was hence based upon the earlier Keith and Sharpe bullets , while additionally having slight differences from both . Performance . This cartridge is regarded by many as an excellent self - defense round . The hollow point version enjoys a reputation of being the gold standard of stopping power among handgun cartridges and an " extremely reliable one shot stopper . " For big game , such as ungulate s and bears , which have a substantially sturdier build than humans , it is inferior to the . 500 Smith & Wesson , . 50 Action Express , . 44 Magnum , . 454 Casull , . 41 Magnum and other larger magnum rounds . Still , it is a fine small and medium game round and will kill deer very reliably at reasonable ranges if the right loads ( and heavier hollow - point bullet s , and solid semiwadcutter bullets ) are carefully used by a competent marksman . For further comparison , the . 357 Magnum has a higher velocity at than its parent . 38 special has at the muzzle . Its stopping power on game is similar to the . 45 Colt and it has a flatter trajectory . It is a very versatile cartridge , and can be used with success for self - defense , plinking , hunting , or target shooting . Revolvers in . 357 Magnum caliber have the significant advantage of also being able to fire . 38 Special ammunition , with its lower cost , recoil , noise , and muzzle flash . This trait makes . 357 revolvers ideal for novice shooters who are not yet used to firing full - strength . 357 loads but do not want the expense of buying a second lower - powered gun to train with . However , a . 38 Special should not generally be used with any . 357 " automatic " handgun or rifle , such as the Magnum Research [ [ Desert Eagle ] a gas operated semiautomatic pistol ] , since such firearms require the larger recoil produced by firing a . 357 Magnum round to cycle properly . A Desert Eagle chambered in . 357 Magnum has a magazine capacity of nine rounds . It has also become popular as a " dual use " cartridge in short , light rifles like the American Old West [ [ lever - action ] ] s . In a rifle , the bullet will exit the barrel at about , making it far more versatile than the [ [ . 30 Carbine ] ] or the [ [ . 32 - 20 Winchester ] ] . In the 1930s , it was found to be very effective against steel [ [ ballistic vest ] ] s , and metal - penetrating rounds were once popular in the United States among [ [ highway patrol ] ] and other police organizations . The . 357 revolver has been largely replaced by modern , high - capacity [ [ semi - automatic pistol ] ] s for police use , but is still very popular for backup gun use , and among outdoorsmen , [ [ security guard ] ] s , and civilians for self - defense and hunting . Some common performance parameters are shown in the table below for several . 357 Magnum loads . Bullet weights ranging from are common . The JHP loads are popular for self - defense , whereas the heavier loads are usually used for hunting . Loads are available with energies from about , and penetration depths from are available for various applications and risk assessments . " 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 ) . Comparison . [ [ File : Pythons2 . jpg | thumb | [ [ Colt Python ] ] s in 8 " and 6 " barrels ] ] [ [ File : Colt 357 . JPG | thumb | 1956 made Colt " 357 " Magnum ] ] The . 357 Magnum was a direct competitor with the [ [ . 38 Super ] ] , which was designed for semi - automatic pistols . Ballistic performance for the two rounds is very similar . However since the . 357 is usually chambered in revolvers , it can be shot in barrels longer than one would normally find in automatics , giving it an increase in performance . In terms of accuracy , the . 357 Magnum has at least the same potential for precision shooting as the benchmark . 38 Special [ [ wadcutter ] ] round — indeed , a good . 357 Magnum revolver will happily shoot . 38 Special wadcutter ammunition with good results . It is this accuracy and power , and the versatility of also being capable of using less - expensive , milder . 38 Special ammunition , that makes a . 357 Magnum revolver an excellent gun for many different disciplines , from precision shooting to long range falling - plate events . It is an excellent round for those considering [ [ handloading ] ] ammunition , as it is economical and consistently performs well . As mentioned above , the . 357 Magnum was developed from the earlier . 38 Special . This was possible because the . 38 Special was originally designed to use [ [ Gunpowder # Gunpowder ( black powder ) | black powder ] ] , which requires two to five times as much powder by weight to produce the same velocity with the same bullet as does the much more efficient [ [ smokeless powder ] ] . Thus the . 38 Special has a relatively large case . The [ [ 9x19mm Parabellum | 9mm Parabellum ] ] was introduced the same year ( 1902 ) but was originally designed for [ [ smokeless powder ] ] , and for higher pressures ( ~ ) . It therefore produces considerably more energy than the . 38 , despite its case having less than 1 / 2 the powder capacity . Most 9 mm powder charges fill the case to the base of the bullet , and some are heavily compressed . Many . 38 Special loads use the same powders , in similar charge weights , but because the case is so much larger , those charges only fill the case about half full . Light target loads with fast burning powders may only fill the case perhaps 1 / 8 full . Filling the case with slower - burning powders produces much more power , but also much more pressure ; far too much pressure for older , smaller - frame revolvers chambered in . 38 Special . It was to accommodate these high - pressure , high - power loads that the longer . 357 Magnum , together with the stronger revolvers designed to handle it , were developed . The [ [ . 357 SIG ] ] that was developed in 1994 was named " 357 " to highlight its purpose : to duplicate the performance of . 357 Magnum loads fired from barreled [ [ revolvers ] ] , in a cartridge designed to be used in a [ [ semi - automatic pistol ] ] . Performance is similar to the [ [ 9x23mm Winchester ] ] . The . 357 SIG provided a self - defense cartridge close in performance to a 125 gr . 357 Magnum , but from a semi - automatic pistol with greater ammunition capacity . References . Notes External links . [ [ Category : 1934 introductions ] ] [ [ Category : Magnum pistol cartridges ] ] [ [ Category : Pistol and rifle cartridges ] ]