9×21mm
The 9×21mm pistol cartridge (also known as the 9×21mm GP, 9×21mm IMI, 9mm IMI, 9×21mm Italian, or 9mm Italian) was designed by Jager (Loano, Italy), then adopted and commercialised by Israel Military Industries for jurisdictions where military service cartridges, like the 9×19mm Parabellum, are or were illegal for civilian purchase (i.e. France, Brazil, Mexico as well as Italy until 2021, when the 9×19mm was legalized for civilian use).
Also recorded as 9×21mm IMI · 9 x 21mm · 9 mm IMI
9×21mm

Costas-1963 · CC BY-SA 4.0
- Name
- 9×21mm
- Field
- pistol cartridge
- Period
- 1984
- Region
- Israel
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Documentary summary
The 9×21mm pistol cartridge (also known as the 9×21mm GP, 9×21mm IMI, 9mm IMI, 9×21mm Italian, or 9mm Italian) was designed by Jager (Loano, Italy), then adopted and commercialised by Israel Military Industries for jurisdictions where military service cartridges, like the 9×19mm Parabellum, are or were illegal for civilian purchase (i.e. France, Brazil, Mexico as well as Italy until 2021, when the 9×19mm was legalized for civilian use).
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Authority files
wikidata · Q649326 · wikipedia · 9×21mm
In this article
Key facts
Key facts
• Name — 9×21mm • Type — Pistol • Origin — Italy Israel • Designer — Franco Benvenuti Agency (Italy) and Israel Military Industries (IMI) • Production Date — 1980–present • Is Si Specs — yes • Parent — 9×19mm Parabellum • Case Type — Rimless, tapered • Bullet — 9.03 • Land — 8.79 • Neck — 9.63 • Base — 9.93 • Rim Dia — 9.96 • Rim Thick — 1.27 • Case Length — 21.15 • Length — 29.75 • Case Capacity — 1.01 • Rifling — 254 mm (1 in 10 in) • Primer — Small pistol • Max Pressure — 235.00 • Is Si Ballistics — yes • Bwunit — gram • Bw1 — 7.45 • Btype1 — FMJ • Vel1 — 390 • En1 — 570 • Bw2 — 8.00 • Btype2 — FMJ • Vel2 — 360 • En2 — 518 • Balsrc — C.I.P.
History
History
Based on the 9×19mm Parabellum cartridge, the case was lengthened from 19.05 to. The bullet sits slightly deeper in the case, which results in almost the same overall length as the 9×19mm Parabellum cartridge (29.69 to). The cartridge was designed by Erasmus Giordano & Armando Piscetta to be used for civil purposes with large pistols (also those designed for.45 ACP). It was named "9 mm GP". The users were not enthusiastic at the very beginning for several reasons, such as the fact that barrels had to be modified. During the 1980s, Israel Military Industries (IMI) started to use 9×21mm and received permission to import the UZI Defender (also called Micro Uzi) into Italy chambered for 9×21 IMI. It was the first official commercial launch for the 9×21mm. From that period on several companies in Italy started to sell 9×21mm pistols and ammunition. In just a few decades, the 9×21mm GP or 9×21 IMI became roughly 80% of the civilian small arms market in Italy.
Competition use
Competition use
As it is a rimless round, the 9×21mm is used in USPSA/IPSC competition in open class firearms. A rimless case is preferred because, unlike semi-rimmed or rimmed cartridges, it will not tend to lock together with other rounds in a double-column magazine, resulting in a malfunction. As other.38 Super–based rimless cartridges became available, the 9×21mm decreased in popularity in the United States for competition use, but it is still widely used in many other parts of the world.
Synonyms
Synonyms
• 9×21mm IMI • 9 mm IMI • 9mm Italiano • Winchester 9×21mm WIN [124-gr. bullet]
Cartridge dimensions
Cartridge dimensions
The 9×21mm has 1.01 ml (15.5 grains H 2 O) cartridge case capacity. 9×21mm maximum C.I.P. cartridge dimensions All sizes in millimeters (mm). The common rifling twist rate for this cartridge is 254 mm (1 in 10 in), 4 grooves, Ø lands = 8.79 mm, Ø grooves = 9.03 mm, land width = 3.80 mm and the primer type is small pistol. According to the official C.I.P. (Commission Internationale Permanente pour l'épreuve des armes à feu portatives) guidelines, the 9×21mm case can handle up to 235 MPa piezo pressure. In C.I.P. regulated countries every pistol cartridge combo has to be proofed at 130% of this maximum C.I.P. pressure to certify for sale to consumers.

Cartridge 9mm x21
Grasyl
Places
Named by the record
Places
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- Israel
Primary material
Documents and archives
authority record
- Wikidata, structured authority record Q649326: 9×21mm
Unverified · Wikidata
reference work
- “9×21mm”, English Wikipedia, consulted as further reading
Reputable secondary · Wikipedia
Citations
References
Each reference names the institution holding it, so a reader may go to the document itself.
authority record
Partially resolvedreference work
Partially resolved
The Encyclopedia exists whether or not anything is for sale. Corrections are recorded rather than overwritten, and every version of this record is kept. Published 14 August 2026.
Elsewhere in Militaria
6,095 published records in this field, each with its sources named.
- 9.5×57mm Mannlicher-SchönauerTerminology
- 9×18mm MakarovTerminology
- 9×18mm UltraTerminology
- 9×19 mm ParabellumTerminology
- 9×21mm GyurzaTerminology
- 9×23mm LargoTerminology
- 9×23mm SteyrTerminology
- 9×23mm WinchesterTerminology
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