justleesa,
The primer is what makes the round go off, so dropping it on the primer could do just that. However, primers are recessed a small amount into the brass case so just dropping it on that end is not likely to trigger it. However, if it were dropped on something which struck the primer directly, like a small stone, protruding nail head, etc., it could very well make it fire.
The round would not likely have much effect on anything at this point, if it did fire. The expanding gases from the round would expelled the bullet from the case, but it would not have any particular direction, lacking a barrel. The gases would rapidly escape from behind the bullet once it was dislodged from the case, leaving minimal force behind the bullet to propel it. It is possible that the case could rupture at this point sending small pieces of brass everywhere.
What makes a firearm work so well is that the bullet is guided by a barrel to give it direction. The gases escaping from the case once the round has been fired continue to build and are trapped between the case and the bullet, which is actually plugging the barrel, to a degree. The case does not rupture here as it is surrounded by the barrel, preventing this from happening. As the gases expand the bullet is pushed more rapidly down the barrel. Once the bullet leaves the barrel, the gases are vented behind the bullet, and cannot give it further velocity.
Lacking the barrel to trap the gases and give the bullet direction, the round is way less dangerous than when in a firearm. However, this is not to say you cannot be killed or injured seriously if it should accidently fire. It just that your chances are reduced a lot.
Care should be taken when handling any sort of ammuntion.
