You have to keep in mind these people's fundamental stance. From a 'sh**t-scared of almost everything in the world' perspective, the practical uses actually are, as krazen said, pretty obvious.
I would suggest that these NRA types, and, well, thousands of everyday law enforcement who use such magazines might not be afraid of a pacifist like Nathan, but might be afraid of a handful of gangbangers coming to rape their women and children.
lol
The sad part is that krazen's mentality is pretty universal amongst the NRA-set, even in backwoods parts of the country where criminal behavior outside of meth production and domestic abuse/child abuse is pretty rare.