History of the .600 Overkill Cartridge by Dr. Robert L. Garnick
The .600 Overkill was conceived specifically as the most powerful cartridge that could be chambered and fired in a modified CZ550 action to produce a firearm of acceptable weight (12-13 lbs) for the hunting of dangerous game. Unlike the .50 BMG cartridges and their variants (which have been converted into .600 caliber), the .600 Overkill was specifically designed as a sporting cartridge whose lineage can be directly traced to the widely accepted Big Bore British NE cartridges such as the .577 NE and .600NE. While conceptually similar to a .600NE with the rim removed and a magnum belt added, the reality is that as far as the inventor knows, this cartridge design has never been previously considered. This most probably is due to the difficulties inherent in adopting bolt action rifles to the rimmed .600 NE caliber. The .600 Overkill cartridge was designed to produce a muzzle velocity of 2400 fps with a 900-gr Woodleigh bullet for well over 10,000 ft-lbs of muzzle energy. The cartridge was the result of the inventors somewhat unhappy experiences with converting a CZ550 from .416 Rigby into a 585 NYATI. These experiences, particularly with the resolution of deficiencies in the NYATI case design served as a basis for the .600 Overkill. The .600 overkill was based in turn on the observation that 585 Nyati basic brass (cylindrical .577NE brass with the rim removed) uses a .640 rim diameter and is 3.25 inches long would just fit a .620 Woodleigh, 900 gr bullet. Unfortunately, this combination would not allow for a shoulder to be produced for head spacing and thus the headspace of the .600 Overkill could only be accomplished by the addition of a belt. The case OAL was reduced to 3.00 inches in order to produce a COL of 3.600 using the woodleigh 900-gr bullets. This proved to fit the CZ 550 magnum action and resulted in smooth feeding. Lathe turned brass cases were produced early in July 2002 to test the feasibility of the design and met with a great deal of enthusiasm amongst members of the Big Bore Forum at
www.accuratereloading.com . Many of these members have extensive big bore rifle building experience as well as considerable experience in hunting dangerous game with .50 and .600 caliber rifles. One of these members was reportedly a 16-year-old firearms enthusiast from Sweden (who posted as OVERKILL) who was bent on a quest to own the world’s most powerful weapon for hunting Swedish elge(moose) and bears. In a good-natured jest, the name .600 Overkill was given to this cartridge and endorsed by the forum members. Due to his age OVERKILL was proscribed from owning such a weapon. Nevertheless, seven members of this forum are now in the process of building .600 Overkill rifles.
Based on the Lathe turned cases, a chambering reamer was produced by PTG and 3 groove .600(1:20) barrels produced by Pac-Nor. Dieter Horneber is producing the brass for the .600 Overkill in Germany and American Hunting Rifles (AHR) has done the R&D on adapting the CZ550 action to this cartridge. AHR is confident that they can build completed rifles to these exacting standards. The first of these completed rifles is expected to be available in Jan/Feb 2003.
I was looking through my wholesale sports catalogue and I noticed for one particular rifle that it came in a few different cals and I don't know which one to go for. The cals were 375h&h, 405win, 416 rigby, 458win and 458 lott. I've already got the 458win and I love shooting it so I'd probably pass on getting another gun in the same cal. I've heard a lot of great things about the 375h&h here on cgn. What about the others though? I've heard of the 416 rigby and the 458 lott but never heard of the 405win. Someone once mentioned to me that the 458 lott was like the big brother to thr 458win. Any thoughts and opinions are greatly appreciated. Thanks.
