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.303 Magnum
Type Rifle
Place of origin England
Production history
Designer W.J. Jeffery & Co
Designed 1919
Produced 1919
Case type Semi-rimmed or rimless, bottleneck
Bullet diameter .312 in (7.9 mm)
Neck diameter .345 in (8.8 mm)
Shoulder diameter .462 in (11.7 mm)
Base diameter .530 in (13.5 mm)
Rim diameter .557 in (14.1 mm)
Case length 2.35 in (60 mm)
Overall length 3.35 in (85 mm)
Ballistic performance
Bullet weight/type Velocity Energy
174 gr (11 g) 2,850 ft/s (870 m/s) 3,050 ft·lbf (4,140 J)
Source(s): Cartridges of the World.[1]

The .303 Magnum is a bottleneck centerfire rifle cartridge developed by W.J. Jeffery & Co and introduced in 1919. It was produced in both semi-rimmed and rimless versions.[2]


The cartridge was designed by Jeffery for target shooting, and was used for some time by the British Match Rifle Committee.[2] The .303 Magnum's case capacity is the same as the .30-06 Springfield, although performance was considered to favour the .303 Magnum. The .303 Magnum had a brief life, only appearing in the Kynoch catalogue until 1930.[1]

The .303 Magnum fires a 174 gr projectile at 2850 fps.

See alsoEdit


  1. 1.0 1.1 Frank C. Barnes, Cartridges of the World, Gun Digest Books, Iola, 2012, ISBN 978-1-4402-3059-2.
  2. 2.0 2.1 Don Davie, The other .303 cartridges,, retrieved 25 Jan 15.

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