A larger powder charge headed down the same sized hole will be more corrosive, all things being otherwise the same.
Think of it like sand.
I there's a limit on how much sand I can force down a opening before the opening wears out. Driving more sand and at a higher velocity down the opening accelerates wear.
So, same diameter (.308) with more powder (300 Win Mag) will always wear the throat faster, no matter what type of powder, even if you "loaded down" the 300 Win Mag to 308 velocities.
