Military rifles (namely .223) see thousands and thousands of rounds, and many are fired through a hot barrel. The M-16 A2 is expected to hold 3 MOA, if not it is replaced. This is not ideal for a target shooter but would due for a plinker. Match shooters replace their barrels at 3000 rounds or the first slight sighn of accuracy loss, but these same barrels which usually still yeild MOA accuracy would be perfect and have many thousands of rounds of life left for an average shooter. As with anything there are extremes but don't listen to the hype about barrel burn out unless you shoot thousands of rounds a year you should never have to worry about it.