Your friend is absolutely right. That's why bullets from magnums "zip right through doing hardly any damage." It's just like the party trick where you pull a tablecloth out from under dishes, plates, glasses, etc. If you do it fast enough, every thing stays in its place.
The reason is that if a bullet is going fast enough, it doesn't have any time to do any damage or expand. As a bullet approaches the speed of light, it probably won't do any damage at all.
Kiddin'....right?
