History of the .358 WSSM Cartridge
Like many states east of the Mississippi River, Indiana has not allowed deer hunting with rifles. Shotguns, handguns, muzzle-loaders, and bows are allowed. Some say this is intended to make the hunt more challenging, thereby promoting growth in the deer population (particularly several decades ago when deer populations were low). Others say it is intended to limit the range of a potential stray bullet. Whatever the case, a traditional deer hunting rifle could not be used in Indiana to hunt deer. However, in 2007, Indiana loosened the restriction slightly by allowing rifles that fire pistol calibers. The Indiana DNR defines pistol calibers as having a minimum bullet diameter of .357., a minimum case length of 1.160", and a maximum case length of 1.625". The intent was to allow rifles that fire cartridges like the .357 Magnum and the .44 Magnum. (Note that this year, the maximum case length has been increased to 1.800".)
However, wildcatters immediately conceived of the .358 WSSM. It is based on the (ill-fated) Winchester Super Short Magnum case, necked up for a .358" bullet. The resulting cartridge duplicates or exceeds the performance of the respected .358 Winchester. The Indiana DNR has become aware of these wildcats and gone along with them. Consequently, the .358 WSSM has become one of the most effective calibers allowed for deer in that state, and there has been a surge of interest in this and similar wildcats.
Winchester's first Short Magnum cartidge, the .300 WSM, was developed in 2001. It used a short, fat case with a rebated rim. By 2005, the WSM line was available in four diameters. They purported to produce magnum performance in a short-action rifle, which allowed for a lighter weight firearm.
In 2002, Winchester took the concept one step further when they produced the .223 Winchester Super Short Action. The WSM case was made about ½" shorter and used with smaller diameter bullets to produce a cartridge with very impressive velocities. In 2003 and 2004, two more WSSM cartridges were developed for a total of three: the .243 WSSM and the .25 WSSM.
The WSSM cartridges have a case capacity similar to that of a .308 Winchester. However, the short and fat arrangement means a powder column that burns more efficiently. The WSM and WSSM cartridges also specify a higher maximum pressure (65,000 PSI). Together, these two factors yield higher velocities.
The WSM cartridges are becoming fairly popular. Unfortunately, the WSSM was cut short (no pun intended) by financial difficulties at Winchester/Browning. The WSSM rifles were being produced in a special "super-short" action to take advantage of extra weight reduction. This adds to the manufacturing complexity and cost by increasing the number of raw parts that must be made and stocked for production. Super-short receivers, bolts, magazine boxes, magazine followers, bottom metal, and stocks must all exist. When Winchester (U.S. Repeating Arms) closed in 2006, and was partially revived over the course of the next two years, production of super-short rifles was never resumed. Today, WSSM rifles are only being produced by a couple of manufacturers of the AR-15 platform, the largest being Olympic Arms.