I have found that I can choose a rectangular stone with sharp edges and get that sound pretty regularly with accuracy within an 8 to 10 foot target at about 40 yards, and if further range is attempted the accuracy breaks down due the slowing projectile, drag, and the instability of irregular shaped ammo.  The ballistic coefficient on a shape like this is very poor if it ever be figured at all.  After all, a round lead cast ball fired from a black powder arm theoretically shouldn't be able to fly accurately and true, because of a poor drag coefficient, however, it does fly quite well in spite of the physical mathematics that states it shouldn't.  The same goes for a bumble bee, some scientists are still trying to figure out why it can fly when the little beast is just not aerodynamically built to do so.  The current theory with many of these men of learning is simply that no one told the humble little bumble that it couldn't, and continues to fly happily in it's ignorant bliss of getting on with it's daily chores.
Anyway back on the subject of sound effects from this very addictive and fascinating hobby, The sounds that most impress me and one I have not achieved, is the cracking sound that I have heard in Barak's video, which I am not sure if it came from his sling or his projectile.  If it can be produced on regular basis it would certainly impress any onlooker as well as speed and accuracy can.  Another sound which my slinging habit has achieved on two occasions is the sound of the retention and release cords tensioning to make a noise similar to a bow being dry fired (please don't dry fire bows it's very bad for them.) I suppose if this hobbie floats your boat for the cool sounds it can make, then do it. Just make sure you put fraycheck on your sling pocket if it is braided or better yet, reserve a leather pocketed sling for your sound effect aspect of this hobby.  One can have many different reasons for the pursuit of this activity, accuracy and power, to uncover cultural and historical techniques, the endeavor of scientific explanation of the physical world around them, survival and primitive living, but most of all to me it is just so darn fun!

Happy Slinging

BarneyRubble

Quote:

....cracking is from free end of sling.  Make yours with a little tassel beyond the knot, and you'll get some cracking, too.   It sort of becomes the sign of a good toss.  mgreenfield

Actually, I read a while back that scientists have now figured out how the bumblebee manages to fly. I don't know any details, just that they solved the mystery.

Every once in a while, one of my odd-shaped rocks will take off and hover.  It's really neat to see.

I personally think the bumblebee flies due to sheer determination.