What happens to them all?

The bullet will not come at the same velocity it left the rifle barrel - it will come down at its terminal velocity. This would still be fast enough to kill though especially as it has a high probability of hitting the top of the head.

People are killed in the middle east on a regular basis because of falling ammunition.

The probability of death from a falling round is extremely low - but it will kill.

HM Forces are trained to NEVER fire a round into the air - even a warning shot - because the risk is present.

the comment about falling bullets not being a danger is completely ludicrous

of course they can do extreme damage

also bullets are stabilized in flight they spin around their axis so they do not tumble in air as a result the air friction applied to the bullet is minimal much less than a skydiver in free fall and they travel about 200 MPH a bullet accelerating due to gravity will Travel much faster.

odds are the falling bullets Won't hit anybody but if one is unlucky enough to get hit serious injury or death will occurr

They do not have enough power to kill when they come down unless you are one really unlucky SOB.

When a bullet falls after being shot straight up it will come down about 100 mph maybe more maybe less depending on a few factors.

It should not kill someone but it is possible.