Looks like a shorter sling and change the angle of the trigger. That angle will determine how high of an arc it throws, or will slam into the ground a few feet past the Trebuchet. Fun times, we built one about 15-20 years ago with 1000# of tractor weights, a 16 or 18' throwing arm, we were tossing gallon jugs of water 8-900' and somewhere around 120' at the highest arc during the furthest throws.