I do it "wrong", believe it or else...
Shhhh. Don't tell anyone.
I, uhh...[furtive lookaround]
I shoot mine [wince] "gangsta-style". There, I said it.
Having known a guy who had suffered from essentialy a destroyed retina in one eye as a result of a slingshot rubber failure, I'm REALLY reluctant to line those rubber tension bands up with my vision machines, and I don't always have eyes in the fields when I'm sling-shooting.
Another point is that I tend to favor a higher weight-class of projectile than the normal 1/4"-3/8" BB. The bearings rip along quickly, and they're consistent, but I'm unimpressed with their impact energy, and they fail to penetrate into shrubbery well when I'm harrassing a squirrel up-and-down a tree by cracking pebbles through his neighborhood.
I like smooth creek pebbles, about 3/4" across. They hit hard, you see 'em to track 'em, so as to adjust at long range, and they CARRY. Weight=momentum, and smooth-surfaced river pebbles fished out of a gravel bank are plentiful, consistent enough for good results, and they're plenty fast. They're the greatest for long-range ballistic barrage-fire such as hassling ducks wayyy out in the pond/swamp.
DON"T bounce 'em off yer mounting pillars. Cut rubbers, and ultimately, catapult failure from the front is inevitable. That blanked retina rears it's ugly head in my memory here. [--shudder!]
Hokay, technique specifics. Brace is on the right hand/wrist, canted 90 degrees to the left and extended almost straight out in front. Left hand holds a pinch-grip on the pouch, and pulls back alongside my ribcage or hip, about. Right-hand is extended slightly to the left, across my body so that the rubbers are pointed straight out.
Left/right alignment is guaged by looking out over the extended rubber, this actually works easily. Elevation is guaged by checking paralell-ness of the draw to my sightline, plus a little overage for slow trajectory. Awkward as this sounds, it's surprisingly easy to figure out with just a few shots
so long as you can track your ammo in-flight! Feedback is immediate, and with plentiful ammo, you can practice as much as you like.
Granted, the rocks are moving slower than the BB's, but they weigh 4-5 times as much, and they don't slow down to any appreciable degree unless your shooting at extreme range, i.e barrage fire. Slower speed allows for better visual tracking and feedback, also.
I'd never much messed with wrist-rockets or slingshots until just recently. Always got a bit nervous about drawing those thick rubber whips up by my eye, you see. Then my buddy turns up with a couple of slingshots he rooted up outta his garage, and we go to Big 5 for new rubber. He then drags me out to pester squirrels at the park despite my reluctance, and LO! He reveals this shooting technique to me.
Wonder of wonders, hey, this is EASY! And NOWHERE NEAR my eyes! He likes to shoot BB's, which cost cash, but I much prefer the creek ammo which is abundant and free, and in one afternoon I could reliably nail the streetlights along the bike-path at 40-50 feet, most times. (Snap!-whzzzCLANG!...uh, oops.
)
It's a great technique for us wimps afraid to lose our eyesight. The only caveat is to make sure you're not mis-aligned with your right/strong hand when you're at full-extension right before you fire. It's easy to twist the catapult, which makes for pillar hits. Just adjust your grip position so the the bands 're coming straight back off of their posts bfore releasing. Better accuracy, too.
In flight tracking works for guns, too. The day I saw the backs of .38 Specials going downrange at 100 yards, I immediately quit trying to plunk bullets into water jugs at full range, and started to try to loft bullets through a tiny little "hole" in the air at the top of the bullet's arc, about 1/2-way between me and my targets. When I got 'em through the hole correctly, I scored hit. But aI wasn't looking at the targets beyond checking the alignment of the "hole" I was trying to shoot through. With immediate tracking info close at hand, I was able to dial in on the target much easier than I did just shooting off of a rest with a sharply focused front sight and a blurry dirtbank.
I guess that's what tracers are all about, right on the face of it. I wanna fool with summa those sometime...