I have rebarreled enough .22-250's to create myself a storage problem for shot out barrels. The 3,000 round figure is pretty accurate, depending of course on how hot they were loaded and how hot you let the gun get when varmint hunting. Normal .223 barrel life is about 5,000.

This is using .5 MOA as the starting point and 1 MOA as the maximum allowable group size. I went to a Colt AR-15/M-16 armorer's school last May and they were saying that Colt considers the maximum barrel life of one their AR15 barrels to be 35,000 to 70,000 rounds. But their maximum group size requirement is something like minute-of-grapefruit