@Near miss my thought was that if the kids are shooting at targets floating in the fjord then they cant harm anyone on our side of the fjord. If the max range was say 800m then there is a good safety margin so that they cant hurt anyone on the other side of the fjord...
with a max range of 1600m unfortunately it is theoretically possible for a kid fooling around to give someone on the other side a headache by dropping a bullet on their head - not a good enough safety margin.