Properly cared for, and never overheated, I would say 4-5000 rounds.
I should say, barrel life is a rather inexact figure..for one thing, barrel life before what? It won't shoot 1/4 inch groups? Or before it won't shoot 1.5 inch groups?
Also, how you treat the barrel is a HUGE factor. If you were to fire 100 rounds, just as fast as you could load and shoot them, I would estimate your barrel life at 100 rounds.
