hi woolyback
you could give the brass a scrub with a wire brush if you are worried about them.there isnt too much you can do about the rust just one of those things with coastal wildfowling
main thing you have to watch for is the shot rusting in the wad because the pellets can fuse together making it a solid shot very dangerous.every now and then i will cut a cart up to see if its got rusty pellets if it does you can kind of assume the rest will so i cut them up and bin them just to be on the safe side