.308 is a far better caliber anyway. 5.56 maims. .308 kills. .308 also has a much, much longer effective range. Unless you are planning on taking 20 mile marches with a backpack full of ammunition .308 is a far superior caliber.

For target practice .223. Is cheapest. It will also stop a pedo jew niggers zogs.

.223 Wylde . Problem solved.