You don’t know much about ballistics. All projectiles start slowing down the instant they leave the gun barrel. There is substantial loss of velocity in only 100 yards for all handgun rounds. A 48 degree trajectory is maximum range and that is quite a bit further than 100 yards even for a handgun round. more like a thousand yards, with peak altitude occuring about 600 yards down range and about 600 yards up.
I think it is safe to assume that the bullet was not fired straight up or at any high angle to have killed that little boy. I was refuting the "Myth Busters" negative finding on this, since we do know that the boy was killed by a bullet that came through the roof. Now, either the boy died of something else, or a bullet came through the ceiling.
I am assuming that the boy was killed by exactly what they thought killed him. "Myth Busters" could be wrong or the trajectory wasn't the same as assumed by that "highly scientific source". Do you belive that something you see on TV just HAS to be fact, refuting all other evidence?
By the way, the figures you are using are related to "maximum effective range". Bullets carry a lot farther than that. The MER is a judgement upon a weapon's use in a military context.