You did not give what case you are using. I assume by the weight of the bullet it is a .308 caliber, but is it a 30-06 or 300 Mag. Even if we knew what the case was, it would be difficult to predict how long your barrel will last. Personally, I think more barrels are ruined by improper cleaning than any other reason. If a bore guide is not used the rod will wear away at the throat/lands until it is useless. Throat erosion is due to unburnt powder going through at very high velocity. The higher the velocity and the greater the volume of powder, the quicker the wear. A "hot" load will wear a throat quicker than a mild one (velocity of the powder). How much you can tolerate as far as shot dispersion is concerned is another factor. If your best groups are .75" and it opens to .9"; can you be satisfied or not? If not, then it is time to replace the barrel, if you can live with it, then you are still good to go. When would you replace it, when it reaches 1"? It all depends on what you will tolerate. I am guessing here, but I would think with a 30-06 that you should get 2K rounds out of it as long as you do not get the the barrel too hot, load to highest velocity and use a good bore guide before you have any noticeable deterioration in accuracy. Remember, there is very slight wear, every time a bullet goes down the bore no matter how well it is taken care of. It is very minute but a little each time until it wears enough away to effect accuracy. Every situation is a little different. For some 2K is a more than a life time, for others it could be one season. Good Luck and Good Shooting