Large-cased overbore cartridges that burn huge quantities of powder to achieve their velocities are going to wear throats faster than smaller-cased cartridges of the same caliber. The 7mm Ultra Mag, 7mm STW and 7.21 Fireball are a good deal faster than the 7mm Rem. Mag., but they burn a whole lot more powder to get there. Overall barrel wear will be faster, and they will erode throats much faster.