If a person cleans properly with a boreguide, and protects the crown, easily 2500 rounds. I have a 300win mag that has that in it, and still shoots well.

Biggest factor is speed of the ammo. If you reload a 300WSM with 180gr bullets kicking at 3100fps, then its going to erode your throad.

I don't have data to prove it, but I believe the biggest factor is throat errosion is your load size. So with that said, I would say if a person only shot 200gr bullets instead of 150gr, I bet the one shot with 200gr bullets would last longer. Even though the 200gr has more bearing surface. The errosion is mostly caused by heat and pressure, they say.