hmm I tend to run my rifles a bit more aggresively than some do, I average about 25 rounds in 18 minutes or so (no way you can hold that barrel or would even want to) from my 7WSM, go to the pits and pull targets for an hour or so then do it again.
All that having been said, I still got 1,700 rounds from that Kreiger barrel before it went noticably south (right in the middle of my last match of course). I've got another one and am in the process of swapping those barrel to teh second one now.
JeffVN