9×21mm

9×21mm (left) and parent 9×19mm Parabellum (right) cartridges

Type

Pistol

Place of origin

Israel

Production history

Designer

Israel Military Industries

Specifications

Parent case

9×19mm Parabellum

Case type

Rimless, straight

Bullet diameter

9.03 mm (0.356 in)

Neck diameter

9.63 mm (0.379 in)

Base diameter

9.93 mm (0.391 in)

Rim diameter

9.96 mm (0.392 in)

Rim thickness

1.27 mm (0.050 in)

Case length

21.15 mm (0.833 in)

Overall length

29.75 mm (1.171 in)

Case capacity

1.01 cm³ (15.6 gr H₂O)

Rifling twist

254 mm (1 in 10 in)

Primer type

Small pistol

Maximum pressure

235.00 MPa (34,084 psi)

Ballistic performance

Bullet mass/type	Velocity	Energy
7.45 g (115 gr) FMJ	390 m/s (1,300 ft/s)	570 J (420 ft·lbf)
8.00 g (123 gr) FMJ	360 m/s (1,200 ft/s)	518 J (382 ft·lbf)

Source(s): C.I.P.

The 9×21mm pistol cartridge (also known as the 9×21mm IMI or 9 mm IMI) was designed by Israel Military Industries for those markets where military service cartridges, like the 9×19mm Parabellum, are banned by law for civilian use, like in Italy.

Based on the 9×19mm Parabellum cartridge, the case was lengthened from 19.05 to 21.15 mm (0.750 to 0.833 in). 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 29.75 mm (1.169 to 1.171 in)).

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 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 the rest of the world.

The 9×21mm has 1.01 ml (15.5 grains H₂O) 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.

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Wikipedia