Shoot already
Take the shot. Hold 1-2" high and squeeze it off.
Or leave your ground blind where it is and put up a tree stand at a different angle 30 yards closer one night. Get nto your stand an hour earlier than usual. Be still.
No mans land? If you can shoot 1" at 150 with a .243, there IS no 'no mans land' at 180 yards.
However I can appreciate not taking a shot you're not comfortable with. Something tells me there's another factor involved here.