five foot staff = how long is the sling ? lol
Height of person is less relevant than how fast they can move their arms. Although with a staff sling, it's generally the last part of the arc where you really put the oomph in.
For example i can probably throw something further than some skinny wimp who is a lot taller than me
Unless that person happens to be hathor julius bjornson, who is around 7 feet tall in footwear and one of the three strongest men in the world. More importantly he has enormous explosive strength.
I reckon he could make 500 metres with a 5 foot staff and 5 foot sling attached.
remember the length of the sling is at least as important as the length of the staff.
Also it depends on the type of staff sling.
I prefer a hoopack style. Which is a staff with a Y shaped end piece.
Easier to make and it adds more spin to your missile, which - with the right missile - will add distance and accuracy.
Staff slings are great - but they do add a lot more variables to a question like: 'how far...'