I used to salvage bullets at the range until some old timers told me that tiny particles of sand and grit don't separate out of the mix and will "sandpaper" your bore. I stopped salvaging after that.
YMMV.

As far small size bullets, I even cast 80 gr. .223 bullets for my Ruger #3 single shot and bolt rifles. Even at 1500 fps, they really tear up rabbits and other small varmints.