RE: Shot gun ?
DM
Regardless if it is lead or not, it is still being shot through that hard steel barrel at 1300-1500fps. Will it wear down the rifling on the first load? No, but it will wear the rifling down over time and use. How much wear? I don't care to find out. Any wear will effect the accuracy and performance intended by the rifling. If you choose to do this that is your choice. I won't and have talked to others who would agree. To each his own, but I still recommend not doing it.