Hello WildAtHeart,
In my opinion, and after more than 25 years of experience like judge referee, the size that you use can consider acceptable, although the normal is that the slingers use stones something smaller, it is also true that there are them that they use bigger, in our competitions it is not specified the size of the stones, each slinger it can use the size that he wants.
It is important to keep in mind that the more big it is the stone, smaller distance and more force will have to make the slinger, therefore also the size goes in consonance with physical condition of the slinger.
Greetings,
Vicente
Quote:In one of my buckets of rocks I came across this rock. It was too good to throw! It is almost the exact size and shape of an egg. Sorry about the pictures, they are a little bit fuzzy.