Ok, awesome story, I want some of you guys to try it out!
ok, so I was in my back yard this afternoon for an hour of slinging. I decided to pick up some rocks that would hum just to hear the sound.
This is kinda what I picked up:

The one on the bottom is what I usually throw.


Anyway, I threw these kinds of rocks and then..........
They stopped humming! I was confused, they were weird rocks. So I threw some even longer ones like these:

And they flew sooooo straight without humming. Then, watching the rock more closely I discover it was spinning, like a bullet! It was rifling through the air! They were more accurate too. The one on the right works best.
SO, I tried to throw the same kind of rocks with my normal style, but it didn't work. I think the Balearic style I just started using actually makes the rocks spin right!
I want to see if you guys can try this too. Give it a try! Its really awesome!
 
EDIT: I guess I was really pumped about figuring this out. If you guys already have, then awesome, hopefully my pictures of stones that work for me will help others.

Yep it's a good feeling when they rifle. I had the hardest time for years trying to figure out how to rifle every shot. Some guys around here helped me with that though.  
 
To be honest, I am surprised rocks as flat as that work so well. Glad they do though.

I see, FWIW I call those "spikes". And yea not only do they fly awesome, they are also very good for concentrating the most force on the smallest area for hunting. If I ever had to take a head shot on a deer in a survival situation (not sure why I'd need to  )  that is what I would use. I had a 5 ounce one that was perfectly symmetrical and was almost pointed on each end. It looked like a stretched out football. Flies perfect every time.  
 
I'm really glad to see you're so into slinging Carbon. I was a little younger than you when I started and to me it just never gets old, even after all this time.

Yes,putting rifle spin on elongated ammo is the way to go,nice and efficient Try making some of these,from clay,no need to fire them as they'll fly just as good and you'll probably loose them after the first throw at distance,but they're easy to make,and definitely worth the effort IMO.Try to make the symmetrical so they are stable in flight,and don't wobble.Besides lead projectiles these travel the farthest  :

Rifle spin is definitely very cool. I remember when I started my farthest reaching style was greek overhand because it automaticaly puts a spin on the projectile. After asking some questions on here I found out you can do that with almost any style.  
 
However having some cylendrical ammo will definitely help, it's pretty tough getting a rifle spin on a tennis ball.

Hello,
Excuse my naive question but I had searched for its answer on the forum without success... and now this topic brings it back to my mind :
Do you position those "spike" projectiles in the pouch parallel or perpendicular to the main 2 strings ?
(I'd intuitively position them perpendicular... but I'm only a beginner)

Thanks  
Seems logical : releasing one cord will make the bullet roll around a perpendicular-to-the-cords axis... hence positioning the long spike's axis this way.

Do you "riffle-spin" it by giving a quick downward wrist movement to the retention cord just when you're releasing the other cord ?