Four of the six are for shooting at paper. This is because, in addition to the virtues Richard points out, the .308 is exceedingly accurate. In the late 1950s and early 1960s, benchrest shooters used .308s. It was dropped because it recoiled more than the .22s and 6mms and therefore made miniscule groups more difficult, but it would, by God, print miniscule groups. The smallest group I’ve ever gotten with any rifle of any caliber was shot with a .308.