If you don't like the noise, shop elsewhere. Plenty of stores not as noisy.
Where earplugs, or get an IPod and listen to your own noise.
Do a couple hours of target practice at your local rife range before shopping, just leave your guns at home before hand.
As mentioned vandalism and tampering is illegal, and all though against the forum rules (I think, maybe I'll get around to reading them sometime...), it's really not a good idea put up a bunch of stuff kids might do just for fun.