other calibers
some early mini-14 rifles were chambered in the .222 remington cartridge. Since the .222 remington is not completely dimensionally equivalent to the 5.56x45mm, ruger chambered mini-14s for both 5.56 and .222 remington. Civilian firearms chambered in 5.56 are highly restricted in countries that restrict or prohibit firearms that chamber military cartridges (such as mexico). By chambering the mini-14 in the similar but not interchangeable .222 remington caliber, the mini-14 could be sold in those countries.