.600 Overkill

The .600 Overkill is a hunting cartridge designed to fit the CZ-550 action, by American Hunting Rifles.

.600 Overkill
TypeHunting, rifle
Place of originUnited States
Production history
DesignerRobert Garnick
Parent caseNone
Case typeBelted, straight
Bullet diameter.620 in (15.7 mm)
Neck diameter.646 in (16.4 mm)
Shoulder diameter.646 in (16.4 mm)
Base diameter.656 in (16.7 mm)
Rim diameter.640 in (16.3 mm)
Rim thickness.060 in (1.5 mm)
Case length3.00 in (76 mm)
Overall length3.65 in (93 mm)
Case capacity196.6 gr H2O (12.74 cm3)
Primer typeMagnum large rifle
Ballistic performance
Bullet mass/type Velocity Energy
1,000 gr (65 g) FMJ 2,500 ft/s (747 m/s) 13,877 ft⋅lbf (18,814 J)
1,000 gr (65 g) Solid brass 3,000 ft/s (914.4 m/s) 19,982 ft lbs (27,091.954 J)
Source(s): 470MBogo[1]


The .600 Overkill was designed by Robert Garnick of Las Vegas, Nevada. The case is a custom, with a belt, .683 in (17.35 mm), added for headspacing and the rim to fit that of the .505 Gibbs .640 in-(16.26 mm) size, bolt face.

This cartridge was intended to fire the largest bullet able to fit in the CZ-550,[1] and was designed specifically for the purpose of elephant hunting. The CZ-550 is able to fit two cartridges, with slight alterations. The .600 Overkill fires a 900-grain (58 g) bullet at more than 2,400 ft/s (730 m/s),


  1. ^ a b McCarthy, Daniel. "Mini Compendium of Big Bore Cartridges". 470Mbogo.com. Archived from the original on 1 September 2010. Retrieved 4 September 2010.