I wonder how far the shots were that killed folks at the University of Texas in 1966? Not just in length but factoring the distance downward from the Tower? He was picking off people that were literally blocks away.
Charles Whitman’s longest lethal shot was scored on Roy Dell Schmidt, an Austin city electrical service man who had been stopped by a police barricade on the south side of 21st Street. He was shot and killed while trying to leave the area. While I do not have the exact slant range, the ground distance between the center of the roper and where Schmidt was killed is about 988 feet or about 330 yards. If you want to give him the maximum benefit of the doubt and pretend he was on the very tip top of the structure, the maximum range at which he was hitting was 1034 feet or 345 yards (all values Roy fed up.)
The furthest victims were roughly 1500 feet away and he was 241 feet up on the tower. So somewhere are 1518 feet away from his targets. The furthest away ones at least. Others were significantly closer.