4.38×30mm Libra

The 4.38×30mm Libra (.17 Libra) is a centerfire cartridge designed for use in personal defense weapons.

4.38×30mm Libra
TypePersonal defence weapon
Place of originCzech Republic
Production history
DesignerVlastimil Libra
ManufacturerCzech Weapons (ČZW)
Parent case.22 Hornet
Case typeRimless, bottlenecked
Bullet diameter4.28 mm (0.169 in)
Neck diameter4.90 mm (0.193 in)
Shoulder diameter6.88 mm (0.271 in)
Base diameter7.56 mm (0.298 in)
Rim diameter7.65 mm (0.301 in)
Rim thickness1.24 mm (0.049 in)
Case length30.10 mm (1.185 in)
Overall length41.00 mm (1.614 in)[1]
Maximum pressure430 MPa (62,000 psi)CIP
Ballistic performance
Bullet mass/type Velocity Energy
45 gr (3 g) Spitzer 2,300 ft/s (700 m/s) 528 ft⋅lbf (716 J)
Source(s): Small Arms Defense Journal


It was designed and has been manufactured by ČZW for use in their ČZW-438.[2]

The cartridge is based on a .22 Hornet cartridge converted to a rimless design and necked down to .17 calibre.[3] The .17 Libra has been standardized by C.I.P. to a pressure of 4300 bar.[1]


  • .17 Libra [4.38×30mm]: A rimless varmint hunting and sport-shooting cartridge.
  • .17 Rimmed Libra [4.38×30mmR]: A rimmed varmint-hunting and sport-shooting cartridge for use with break-open actions.
  • .17 Libra Magnum [4.38×??mm]: A longer, more powerful rimless round for use in pistols or Personal Defense Weapons.

See also


  1. "17 Libra" (PDF). C.I.P. TDCC. Retrieved 18 July 2013.
  2. Czech Weapons Product Page http://www.czechweapons.com/en/czw-438/
  3. ".17 Libra". municion.org. Munición. Retrieved 18 July 2013.

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