Only Southern chickens need grits. Just kidding! You mean grit, H. Freeranging chickens probably don't need the grit if they can find small rocks/pebbles/stones on their own. Oyster shell, maybe, but only for the laying hens after they start laying, not before.
Totally agree with speckledhen.........mine free range.they get enough grit....I do oyster shell to laying hens........thats all. Nature works great for all if freeranged