You're kidding, right??? Absolutely none!!! Harry Pope used the same barrel & brass case to fire over 40,000 rnds. Yes you can lead a barrel if you try to shoot cast bullets at jacketed bullet velocity's but that can be removed & you start shooting again so that is no more "damaging" than copper or powder fouling. Use cast bullets as they are designed to be used & you'll have NO trouble & be able to shot a LOT more for the same $. There is reams of helpful cast bullet shooting info out there.
Cheers