Ive rained shot on the tin roof shed thats beside our dove field plenty of times out around 150yd. Im sure they will go farther with the right angle. Ive also had them rain down on me too, when multiple shooters are in the same field. Like mentioned above, at 100yds the pattern is really spread out, and its very unlikely you'll be hit with more than a couple shot.
The best way to tell how far the shots travel and at what pattern they will be in at what distance is to find a big pond or other body of water that is unoccupied and smooth(no wind). Then pick your distance and elevation, and let the shots rain. My dad and his buddy used to do this when trying different chokes.