pretty sure MG42, Vickers, Dshk? all out-range snipers while in buildings.
though it could be a bug, I'm seeing MGs fire well outside their "range cone" pretty often.
All UI displays of weapon/scatter ranges are inaccurate and only a rough estimate.
In buildings, the arc is measured from the center of the house, not the MG in whichever window it happens to be in. Therefore, it appears that the MG is firing outside its arc when in reality the arc is incorrect.