I'd have to defer to some of the members who have more historical knowledge for details but here is the scenario I concocted from what little slinging history I have read:
You are a slinger and part of an army approaching an enemy fortification... you (and your fellow slingers) are ordered to the forfront upon approaching the castle to be the primary "siege engine". The enemy is clustered behind their walls and concentrated immediately behind them. Your detailed instructions are to drop stones immediately behind the wall so they rain down upon the enemy soldiers.
At the slingfest we will use a section of a canal running across the back of the property... we will place two flags on the canal bank marking the extremitites of the "enemy fortification" (and possibly two yellow poly ropes across the surface of the canal to aid the score keepers). Out of several to many casts (TBD), see how many you can splash in the water (the canal is 40-45 feet wide and represents, for this competition, the "clustering of the enemy soldiers"). The range is relatively extreme TBD) , the angle of the shots will need to be relatively high and the stones need to come down "upon the enemy" (splash in the water) in order to be scored as a "hit". Just another shooting game...
I metioned in an earlier post about laying siege to a local house of ill repute in my mis-spent youth. The target was a metal awning running along the "front" of the house's entrance. After the law arrived I adjusted my fire to drop stones on the roof behind the awning... (farther away from our location) the roof was about 50-60 feet deep (an old commercial building on the main drag of an old gold mining town... the "house's" entrance was actually on the back of the building, on the top floor, and we were about a block away and on up the side of the "gulch" on a hill overlooking it all.
I tried to find a similar setup (house of ill repute) but thought it better to stick to the canal out back.
Attached is a photo of the range and landing area (canal) looking down on them from the bluff which is above and behind them both. The "point blank" range will be in this same area with the targets just above the two small structures. Our home is shown with the garage/guest quarters (bedroom, toilet & shower, and four bed "bunk-room") and "north shop" (the photo is facing North). The camper and a small trailer also serve as additional sleeping areas. The distance from the road (runs left to right, paved and "way out front") to the canal is about 1500 feet so we'll be able to make the "siege casting" distance as far as we want... (did I hear "length of someone's arm???)