In the absense of of all those trillions of pesky drag producing air molecules (atmosphere), a bullet would indeed land with a velocity identical to that which it was launched. So if you fired that bullet straight up on the moon, you could be in for a very bad (albeit BRIEF) headache in few seconds!

(Un)Fortunately, Earth's atmosphere literally "gets in the way" of the bullet, causing it to slow down dramatically once it leaves the muzzle. The terminal velocity depends on the aerodynamic efficiency (BC) of the bullet based on how it's falling (point v. base down, or tumbling).

Let's just put it this way, if bullets fired into the sky were dangerous when they landed, the Muslims would have wiped themselves out by now.

Mike