What is the trajectory used to determine these distances?
I would assume 45 degrees as that would provide the maximum distance between shooter and landing zone.
Its specific to bullet weight and powder charge , and a ton of variables. They are saying 55-70 degree angle which is still gonna put a lot of potential into the equation.
From looking on the map at the link my first suspicion was “it had to come from across the river”. Folks on the other side celebrating, shooting off over the water probly (or not even) thinking its safe.