9mm Winchester Magnum

{{short description|Handgun cartridge}}

{{infobox firearm cartridge

|name= 9mm Winchester Magnum

|image=

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|origin= United States

|type= Handgun

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|wars=

|designer= Winchester

|design_date=

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|parent=

|case_type=Rimless, straight

|bullet=.355

|neck=.379

|shoulder=

|base=.391

|rim_dia=.394

|rim_thick=.050

|case_length=1.160

|length=1.575

|case_capacity=

|rifling=

|primer=

|max_pressure=45000

|pressure_method=CUP

|filling=

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|yield=

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|bwunit=

|bw1=115

|btype1=MC

|vel1=1450

|en1=537

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|balsrc=SAAMI {{cite web|title=SAAMI - Velocity and pressure data / centerfire pistol and revolvers cartridges, p. 11 |url=http://www.saami.org/specifications_and_information/publications/download/205.pdf |access-date=13 May 2012 |url-status=dead |archive-url=https://web.archive.org/web/20131016171817/http://www.saami.org/specifications_and_information/publications/download/205.pdf |archive-date=16 October 2013 }}

}}

The 9mm Winchester Magnum, which is also known as the 9×29mm, is a centerfire handgun cartridge developed by Winchester in the late 1970s. The cartridge was developed to duplicate the performance of the .357 S&W Magnum in an auto-pistol cartridge.{{cite web|last=Taffin|first=John|title=Taffin Tests 9mm Magnum|url=http://www.sixguns.com/tests/tt9mag.htm|work=sixgun.com|publisher=John Taffin|access-date=15 May 2011}}

The first handgun which chambered the cartridge was the Wildey pistol. Since then, Thompson/Center and LAR Grizzly Win Mag have produced barrels chambered for this cartridge and AMT chambered their Automag III{{Cite web | url=http://world.guns.ru/handguns/hg/usa/amt-automag-ii-v-e.html | title=AMT Automag II-V | date=22 October 2010 }} for it too, but the cartridge never reached the popularity enjoyed by other handgun cartridges.{{citation needed|date=October 2015}}

Starline Brass in Sedalia, Missouri, still make brass for this cartridge, although much of its production is now used to make 9mm blank firing cartridges for firearms chambered for 9×19mm, as this is easier to accomplish than using .223 Remington (5.56×45mm) cases, which may leave the neck area of the blank too thick to crimp properly. 9mm Winchester Magnum cases can also be trimmed and resized for reloading 9×25mm Mauser.