Yeah...we did slings, too. I got decent but not good. I could make a stone go really far, but not really accurate. It was REALLY hit or miss.
We also tried to learn to use bolas (we thought it was spelled and pronounced as “bolo”)
We used to practice throwing them at trees, flagpoles, and so on. We were in the Philippines, and since there were all kinds of larger wildlife wandering around (monkeys, boars, snakes, monitor lizards and so on) then we were obligated to capture or kill what we could. Well, at least in our minds, and fortunately, we were so inept there was never any chance we would get close enough to any of them to even try.
But we tried to play the part, blazing through the jungle with my machete, hacking at stuff to get through, even though if we walked to the left or right a little you could walk as easily as if you were on a treeless beach.
And after a few minutes of hacking away, you would suddenly realize how sucky it would be to really have to do that for real.
That takes some time to learn. And practice in the back yard. The cops get nervous if you practice in the front yard.
Bottom line is follow through... just like golf. Complete the swing.
/johnny