My point, as I have observed, in NI.
The "fronters" threw rocks, beer bottles and street bricks, while the real "trouble" was filling milk bottles with petrol and rag wicks for the "grand finale".
One must not take rocks lightly.
I used to go out chicken (grouse) hunting with a guy who killed more grouse with rocks than he did with his shot gun. He could toss a rock and nail them right in the head at 25 ft without fail. Rocks are deadly in the right hands.