Although constantly interchanged, “caliber” and “cartridge” aren’t the same. Properly, caliber refers only to bullet diameter. Cartridge is the whole ball of wax: a case of specified dimensions, propelling a bullet of certain diameter within a known weight range and loaded to specific maximum pressure. The cartridge and caliber together determine practical uses, based on bullet weight and shape, velocity and energy, thus range.
There are hundreds of unique rifle cartridges, but for America’s big game hunters there are just seven primary bullet diameters: .224, .243, .257, .264, .277, .284 and .308. Sure, we can argue the .22 centerfire’s efficacy for deer and hogs, but I consider it one of the primary diameters because a lot of people use it, and with heavy bullets and good shot placement, it works.…