Back in the day when it was kids stealing your watermelons - rock salt might have been good. Kids today stealing your whatever, or black bears - rock salt would be foolish.
If you’re a gambling person I suppose you could load the first round with salt and the second with buckshot (humans) or a slug (bears). I prefer to have it loaded with the heavy stuff right from the beginning.
My thought too. First 2 slugs then 00 for 2, then alternate till empty. Bears are fine long as you don’t have to hug them. I’m not keen on rubber bullets either, might just piss it off.