I imagine that bullets with a higher ballistic coefficient (more aerodynamic) are more likely to maintain the energy and rotation with which they were “launched”. The lethal angle for pistols and rifles is probably different.

Also, how heavy does something have to be before it becomes lethal at terminal velocity in general? Pennies (or uncased bullets) dropped off the empire state building are apparently not lethal. Bricks would be a different story.

Bullet size varies a lot however and can range from under 3 grams to over 40 grams. A 40 gram metal object dropped from the empire state building (or fired vertically from a gun) is much more likely to cause enough blunt force trauma to kill even if only at its terminal velocity.

Can we get a myth busters update?

See the movie around 4 minutes. A bullet specially prepared to be fired with low speed still penetrates a block of gelatine (resembling a body) with a distance of around 0.3 meters.
A block of gelatine prepared with a shield on its side (to resemble the skull) is still penetrated with a distance of estimated 0.1 meters.

That’s enough to kill a man and surely enough to kill a child.

Lowering the angle of the shot to around 60 degrees will result in a much larger distance travelled, a few kilometers could even be possible.

The International Action Network on Small Arms has a site at http://www.iansa.org/documents/Aerial07-08.pdf which documents; Children and adults killed and wounded by celebratory gunfire
Total: 15 deaths and 77 injuries in 13 countries

In Puerto Rico, where such celebratory actions are common, news media reports have indicated that approximately two persons die and an estimated 25 more are injured each year from celebratory gunfire on New Year’s Eve. http://www.ncbi.nlm.nih.gov/pubmed/15614232

Spent bullets and their injuries: the result of firing weapons into the sky.
Ordog GJ, Dornhoffer P, Ackroyd G, Wasserberger J, Bishop M, Shoemaker W, Balasubramanium S.

Department of Emergency Medicine, King/Drew-UCLA Medical Center 90059
People often celebrate holidays by firing guns into the air without realizing that this can cause serious injury or death. The present study identified 118 patients treated since 1985 who were hit with spent bullets. Most (77%) were hit in the head. The mortality rate was 32%, which is significantly higher than for all gunshot wound victims in general seen at the same medical center. Laws have been enacted to help prevent people shooting into the sky, but more education and enforcement are required to prevent these serious and preventable injuries. http://www.ncbi.nlm.nih.gov/pubmed/7996596?ordinalpos=7&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum