I had Caia overwatch a double shotgun shot with a fully upgraded (as far as I know) Abramovitch Pump shotgun loaded with hotloaded shells. Instead of firing at the churchers that came into range, she fired at the first churcher that moved, right across the map, inflicting about 40 points of damage (hitting nothing in between, but there was nobody and nothing within the cone range).
Firstly, a shotgun on overwatch ought to fire only at targets within cone range, regardless of percentage settings, and, secondly, it shouldn't hit when fired over such a huge distance (it was a churcher boss map with a katana wielding boss and a victim to be executed. Caia stood some 10 tiles from the top border and fired at a churcher rounding a corner some 10 tiles from the end of the other side of the map).