The article applies to conventional bullets,not paintball projectiles.It's not just the velocity...the density of the bullet is also a factor.As you said,a frozen paintball would be a different story.free_rideman said:That doesn't make sense, since paint ball guns shoot above those speeds, close to 400 fps. Does that mean paint ball guns kill/penetrate people? Plus, as stated a lot, the bullet will probably be falling on its side, thus releasing its force over a great area. Yes, maybe that article is right, but only if the bullet is pointed foward, and hits the person that way.
And even though the bullet doesn't fall back down to earth in a perfect vertical line, it still can easily loose its ballistic trajectory even if fired a little off a vertical shot. This means also that the weather can play a big role, and cause freak accidents. Maybe the bullet should have lost its ballistic trajectory, but the wind blew or something, and caused it to keep on going in a lethal arc. And something opposite could happen too. A bullet that should have kept on a ballistic trajectory could have encounterd some winds or something, and started to tumble.
But at the end of all this, it is safe to say, that bullets fired straight up should generally not be lethal when coming back down.
A falling bullet that follows the same path downward as upward may or may not be lethal.My point was that it is extremely unlikely for this to occur except in a vacuum chamber.Even robbie-boy agrees with that.As you say,the bullet only has to be a fraction of a degree off perpendicular to cause a potentially lethal terminal velocity.