Nice shooting. Barrel life depends on alot of things, # of shots, how hot the loads are, how often it's cleaned (more isn't better), if while using a rod and jag to clean, a proper bore guide is brig used to prevent scratching.
I've read post through out the net saying a new barrel was needed after only 3k. I've also seen reports saying up to around 8k.
I guess the best answer would be, shoot the hell out of it and when your not happy with its preformance then it's time to get a new barrel.