Ah. The problem with
BB guns was that it was fairly easy to find someone outlawing them, or taking them away from you, or telling you "Don't take that out there, it
looks like a gun!"
Well, duh.
However, take 'em they did, and often on a boring summer afternoon we were left completely without projectile-based entertainment, a hideous thing for young redblooded American males. This was before we could have simply fired up a nice game of Quake or Unreal Tournament and had at it with other folks. Throwing rocks was a possibility, but limited, and in any case it's a lot harder to hit bottles with rocks when they're twenty or thirty feet away. Besides, they don't make that same cool pop-tinkle and collapse on themselves, they make more of a paf-tinkle as the rock smashes fragments out for feet.
No good.
Fortunately, there was an answer to be had at the local sporting goods store - the Wrist Rocket. These were nothing more than surgical-rubber slingshots. The difference between them and the classic 'Y' sling of lore was that these had a metal frame which rested a padded crosspiece against the inside of your wrist in order to brace the weapon for much higher power. They were designed to fire small ball-bearing shaped (that is, circular) steel balls, which could be purchased in blister packs for a lot more dough than any sane man ever paid for ball bearings that had failed inspection; however, they'd fire anything roughly that size. Pennies, although they flipped around and went off true. Acorns, although they were too light to travel far. Small pebbles, except that those weren't of regular shape and fluttered around randomly. The best were small marbles; being round, they'd fly well, being hard, they'd break things, and being glass they themselves could be made to powder in the event of a (desired) impact.
The wrist rocket, while not too powerful, could easily match the muzzle velocity and hence power of the manually-pumped BB gun. Further, most wrist rockets would fold their wristguard up against the slingshot for easy concealment and carrying.
Wrist rocket. Don't face down a roadside of empty bottles without one.