.500 A-Square

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.500 A-Square
Type Centerfire/Rifle
Place of origin  USA
Production history
Designer Col. Arthur B. Alphin
Designed 1976
Manufacturer A-Square Company LLC
Produced 1978 to 2011
Parent case .460 Weatherby Magnum
Case type Belted, bottleneck
Bullet diameter .510 in (13.0 mm)
Neck diameter .536 in (13.6 mm)
Shoulder diameter .568 in (14.4 mm)
Base diameter .582 in (14.8 mm)
Rim diameter .603 in (15.3 mm)
Rim thickness .059 in (1.5 mm)
Case length 2.900 in (73.7 mm)
Overall length 3.74 in (95 mm)
Case capacity 141.45 gr H2O (9.166 cm3)
Rifling twist 1 in 10"
Primer type Large rifle magnum
Maximum pressure 63,860 psi (440.3 MPa)
Ballistic performance
Bullet mass/type Velocity Energy
600 gr (39 g) Monolithic Solid 2,470 ft/s (750 m/s) 8,127 ft⋅lbf (11,019 J)
600 gr (39 g) Round Nose 2,470 ft/s (750 m/s) 8,127 ft⋅lbf (11,019 J)
Test barrel length: 26 inches (660 mm)
Source(s): http://www.midwayusa.com/viewProduct/?productNumber=551454 and [1]

The .500 A-Square is a belted, bottleneck rifle cartridge, developed by Col. Arthur B. Alphin in 1976. The cartridge is based on the .460 Weatherby Magnum necked up to accept the .510 in (13.0 mm) bullet; the same as the .50 BMG cartridge. This was Col. Alphin's first commercial sporting cartridge and was designed in “response to some severe problems experienced with the .458 Winchester on safari in Mozambique.”[1]

The .500 A-Square was a proprietary cartridge and the world's most powerful commercially available “sporting” cartridge. However, the .50 BMG is the world's most powerful commercial cartridge for any shooting purpose. The .500 A-Square is used specifically as an African, thick skin, dangerous game, rifle cartridge for the hunting of Elephants and Cape Buffalo as well as a back up gun for professional hunters and guides.


The .500 A-Square cartridge was commercially available from both A-Square and Midway USA as loaded ammunition. The ammunition comes in three loads: 600 grains (38.9 g) Monolithic Solid; 600 grains (38.9 g) soft nose thick jacket and 600 gr (38.9 g) soft nose thin jacket. All bullet/cartridge combination are advertised with a muzzle velocity of 2470 ft/s (753 m/s) and muzzle energy of 8127 ft lbf (11019 J).

In comparison: the parent cartridge, the .460 Weatherby Magnum as commercial loaded with a 500 gr (32.4 g) Monolithic Solid has a muzzle velocity of 2580 ft/s (786 m/s) and muzzle energy of 7389 ft-lbf (10018 J). The .50 BMG as commercial loaded with a 661 gr (42.8 g) FMJ M33 ball ammo has a muzzle velocity of 2750 ft/s (838 m/s) and muzzle energy of 11102 ft lbf (15052 J).

Although there is limited hand-loading information, bullet weights (hunting) are from between 300 gr (19.4) to 647 gr (41.9).

A-Square Company[edit]

In October 2011, A-Square ceased all ammunition operations.


  1. ^ a b Alphin, Col. Arthur B. (1996) [1996]. Alphin, Col. Arthur B., ed. Any Shot You Want (1st ed.). On Target Press. p. 605. ISBN 0-9643683-1-5.