Matt:
It is a matter of word definition. You can destroy (damage beyond using for quality accuracy) in a single morning, if for example, you sit and fire 1 shot per minute for 500 rounds? On a 100 degree day? Yes, you will wear-out thus destroy the barrel. Some argue that it is merely the lands, and that a gun smith can cut the bad part of the barrel off, re-chamber the barrel, or cut the damaged portion, then flip the barrel, chamber the muzzle's end, and reinstall it.
But, yes, for fact, you can wear-out a barrel, damaging the accuracy by damaging the lands, by not allowing sufficient time to cool between shots. For myself, I had my M700, 6mm Rem loaded up to fire 95 grain Nosler partitians at 3,371 FPS. That IMR 4064 powder would heat the barrel right quick. Therefore, I limited myself to 3 shots, and cool the barrel. Just me.
I agree. The .223 is a great choice, but ballistically, it's hard to beat a .243's coefficient, even with light (58 grain) projectiles. My .243 launches 58 grain projectiles at 4,400+ FPS. That's hard to beat, but requires cooling the barrel to maximize the barrel life.
Geno