The 243 Winchester Super Short Magnum (WSSM) was introduced in 2004 as part of Winchester's Super Short Magnum family. It has a very short 1.670-inch case with a .531-inch rim and very fat .5559-inch base diameter. Design criteria were that it had to exceed 243 Winchester ballistics, which it does: A 55-grain varmint load exceeds 4000 feet per second; a 100-grain "big game" load develops 3110 feet per second. The short, fat case allows a smooth, efficient burning curve that is conducive to accuracy, which the 243 WSSM has. It is thus at least as good (and a little bit better) than the 243 Winchester as a combination varmint and big game cartridge. Like the other WSSMs, however, it has not become popular.
