kind of a general question here, and the answer ultimately depends on your hunting needs. For a target gun used in serious competition, the number is going to be a lot lower than that of a hunting rifle. The bottom line is, when the rifle won't consistently hold the accuracy standard you've set for your hunting requirements, it's time to rebarrel. For this combination, I'd guess you'll be able to get several thousand rounds downrange before you'll have a problem that will require rebarrelling. If you're shooting 1000 yard benchrest, you'd be lucky to see 900-1000 rounds before it would need work. I've gotten that sort of life from a 338LM in testing, before it started slipping beyond .5 MOA, at which point I couldn't use that barrel any longer. Still a lot of life left in a barrel like that for hunting purposes, though. Like I said, it comes down to your individual needs.