The .270 Winchester Magnum Wildcat
By Chuck Hawks
The .270 Winchester Magnum wildcat is formed by simply necking-up a .264 Win. Mag. case or necking-down a 7mm Rem. Mag. case to accept .277" diameter bullets, without any other changes. The result is a cartridge that can throw the popular .270 caliber bullets at the same velocity as the .270 WSM in a standard length action without the potential feeding and reliability problems associated with the WSM case design. From the standpoint of hunting rifle cartridge design, the standard length, belted, .270 Win. Mag. wildcat is a far better cartridge than the .270 WSM. The .270 Win. Mag. is also very similar to the .270 Wby. Mag. and it uses a standard 25-degree shoulder, instead of the unusual (but equally effective) double radius Weatherby shoulder.
Approximate ballistics for the common .270 bullet weights of 130, 140 and 150 grains from a 24" rifle barrel, achieved with canister powders available to reloaders within maximum average pressure limits of 52,000 cup or 62,000 psi, should be as follows:
Oddly, this .270 Magnum cartridge does not have a section in the 9th Edition of Cartridges of the World, which covers most of the reasonably well known wildcat numbers. I find this surprising, since the .270 Win. Mag. is both very easy to form and quite a useful hunting cartridge. I will not claim that, as a big game hunting cartridge, it does anything that the SAAMI standardized .264 Winchester Magnum, .270 Weatherby Magnum or 7mm Remington Magnum cannot do, but that is rather good company to keep and American hunters have shown a predilection for .270 caliber cartridges. Recoil and muzzle blast are similar to that of the very popular 7mm Rem. Mag. when shooting bullets of the same weight in rifles of the same weight. Thus, I find the "overlooked" status of the .270 Win. Mag. wildcat rather odd.
Slow burning powders are best with bullets weighing 130-150 grains in the .270 Win. Mag. Examples of suitable powders include IMR 4831, H4831, RL-22, AA 3100, Viht N-165 and Win. WMR. Any of these can be used to achieve the nominal muzzle velocities mentioned above with conventional lead core, gilding metal jacketed bullets from Sierra, Hornady, Speer, Nosler, etc.
The ballistics of the .270 Win. Mag. makes it a fine all-around and long range hunting cartridge. The maximum point blank range (+/- 3") is 300 yards or more when using readily available 130-140 grain spitzer bullets at the MV's listed above. With bullets of appropriate weight and design, it can be used to take all thin-skinned North American game and similar beasts around the world. I have always liked 130 grain bullets in .270 caliber for CXP2 game and 150 grain bullets for CXP3 game. A good 140 grain bullet is a reasonable compromise for combination CXP2 and CXP3 game hunts.
There is a lot to like about the .270 Win. Mag. wildcat and not much to complain about. It is a high performance, flat shooting, all-around hunting cartridge with tolerable recoil in rifles weighing at least 8.5 pounds. As with all wildcats, you must form your own cases and reload your own ammunition, but 7mm Rem. Mag. and .264 Win. Mag. brass is readily available for conversion, which can be done with one pass through a .270 Win. Mag. resizing die with a tapered expanding plug. Use loading data for the .264 Win. Mag. and 7mm Rem. Mag. with 130-150 grain bullets, included in virtually all reloading manuals, as a starting point for working up .270 Win. Mag. loads. Start with light loads and work toward the maximum velocities suggested above, chronographing as you go, and you should have no problems.
Copyright 2010, 2013 by Chuck Hawks. All rights reserved.