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.475 A&M Magnum
Type Rifle
Place of origin United States
Production history
Designed 1958-9
Parent case .378 Weatherby
Bullet diameter .475 in (Bad rounding hereScript error mm)
Neck diameter .502 in (Bad rounding hereScript error mm)
Shoulder diameter .560 in (Bad rounding hereScript error mm)
Base diameter .584 in (Bad rounding hereScript error mm)
Rim diameter .533 in (Bad rounding hereScript error mm)
Case length 2.90 in (Bad rounding hereScript error mm)
Overall length 3.75 in (Bad rounding hereScript error mm)
Rifling twist 1:14
Primer type Boxer large rifle
Ballistic performance
Bullet weight/type Velocity Energy
400 gr (Bad rounding hereScript error g) 3,227 ft/s (Bad rounding hereScript error m/s)9,034 ft·lbf (Bad rounding hereScript error J)
500 gr (Bad rounding hereScript error g) 2,980 ft/s (Bad rounding hereScript error m/s)9,900 ft·lbf (Bad rounding hereScript error J)
600 gr (Bad rounding hereScript error g) 2,500 ft/s (Bad rounding hereScript error m/s)8,040 ft·lbf (Bad rounding hereScript error J)
Source(s): Barnes & Amber

The .475 A&M Magnum is a rifle cartridge developed in the United States. At the time of its development it was considered the most powerful sporting rifle cartridge ever developed.[1] However, as the .475 A&M Magnum was a wildcat cartridge, the .460 Weatherby Magnum continued to be the most powerful commercial sporting cartridge available.

The cartridge and rifle were designed by the Atkinson & Marquart Rifle Co. of Prescott, Arizona, by necking up the then new .460 Weatherby Magnum to accept a .475 in (Bad rounding hereScript error mm) diameter bullet. Fred N. Barnes, the founder of Barnes Bullets for whom the first rifle chambered for this cartridge was made, supplied the bullets. According to anecdotes, Fred Barnes gathered a group of people to demonstrate the rifle. The rifle was fired at the base of a small tree which was uprooted while Fred Barnes who had been shooting from a crouched position on a gravel bed had slid a few feet and ended on his back due to the recoil.[1]

The .475 A&M Magnum was never available commercially, and was only Barnes Bullets and Custom Brass and Bullets provided bullet for the cartridge. Only a small number of rifles have been chambered for this cartridge. Brass is easily fireformed using .460 Weatherby Magnum brass. Dies are available from Custom Brass and Bullets.

See alsoEdit


  1. 1.0 1.1 Barnes, Frank C., ed. by John T. Amber. Cartridges of the World (Northfield, IL: DBI Books, 1972), p.142.


  • Barnes, Frank C., ed. by John T. Amber. ".475 A&M Magnum", in Cartridges of the World, pp. 142–3. Northfield, IL: DBI Books, 1972. ISBN 0-695-80326-3.

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