This doesn't tell you how the barrel was treated. If those 600 rounds were fired rapid fire, the wear to the barrel will be significantly more than if they were slow fired, allowing the barrel to cool to ambient temperature between shots. I suspect actual use was closer to being a five shot string fired at a steady cadence, with the elapse of several minutes allowed between strings while targets were checked. Neither does it tell you what the barrel had been chambered for, a .30 BR cartridge would produce far less barrel wear than a .300 magnum.
In relative terms we can compare barrel life between cartridges by dividing the bullet weight by the powder charge, a ratio of 3:1 is optimal, and if heavy bullets are chosen with medium burning rate powder like 4350, the .300 doesn't come off that bad, certainly better than the .243, but not as good as the .308. Other factors to consider are: what level of accuracy are you prepared to live with? What powder and bullet weight are you most likely to use? What are your shooting habits, do you shoot your rounds quickly, as you might wish to before the light or wind changes, or do you allow time for the barrel to cool every time?
Smith barrels are cut rifled, and there is a theory that a cut rifled barrel can out last a button rifled barrel. This is because cut rifling can be a little deeper depending on the number of passes made by the cutter, whereas the depth of the rifling in a button rifled barrel is dependent on the dimensions of the button.
