I was making an example where you can achieve the same velocity with two different chamberings in the same caliber, and have one barrel shoot out much faster than the other. If you want a specific answer, you need to make a specific question.
How long a barrel will last basically comes down to how much powder you burn with each shot. The velocity you achieve has to factor in barrel length. For a given velocity (within reason) you can achieve longer barrel life by choosing a chambering that burns less powder and using a longer barrel.
There's a saying in racing that is perfectly applicable to this discussion. Speed costs money, how fast to you want to go?
