In the village next to where I live, there is a custom on festive occassions to shoot into the air. Here are my questions:
a) How far can a bullet shot in the air go?
b) How much damage can the bullet do when it lands?
a) I don’t know the answer to your first question, I suppose it would depend on the type of gun the bullet’s fired from. Maybe someone else can come along and help out with that.
b) For the second question, I’ve heard of fatalities from the custom, especially in places like L.A. on New Year’s. I’ve also seen video of people who have to be out on New Year’s (e.g. policepersons) taking cover under freeway bridges during the critical moments around midnight. I’m sure there’d be a lot more fatalities if the most of bullets had enough momentum to break through the roofs of houses.
In addition to Cecil’s column, there was a fairly extensive discussion of it on the SDMB recently:
http://boards.straightdope.com/sdmb/showthread.php?threadid=35099