From Wikipedia...
475 A&M Magnum
Type Rifle
Place of origin United States
Production history
Designed 1958-9
Specifications
Parent case .378 Weatherby Magnum
Bullet diameter .475 in (12.1 mm)
Neck diameter .502 in (12.8 mm)
Shoulder diameter .560 in (14.2 mm)
Base diameter .584 in (14.8 mm)
Rim diameter .533 in (13.5 mm)
Case length 2.90 in (74 mm)
Overall length 3.75 in (95 mm)
Rifling twist 1:14
Primer type Boxer large rifle
Ballistic performance
Bullet mass/type Velocity Energy
400 gr (26 g) 3,227 ft/s (984 m/s) 9,034 ft⋅lbf (12,248 J)
500 gr (32 g) 2,980 ft/s (910 m/s) 9,900 ft⋅lbf (13,400 J)
600 gr (39 g) 2,500 ft/s (760 m/s) 8,040 ft⋅lbf (10,900 J)
Source(s): Barnes & Amber
The rifle is a Mauser bolt action and weights 11 lbs
I only hope that my friend reloaded the cartdiges much lower than the full charges described!
Regards,
