Ry put up two videos of gun related episodes of Myth Busters. They come up with the correct conclusion on the bullet impact effects–which was nice to see. The bullets into the gas tank demonstrated what really happens but then they engage in some conjecture that is unfounded. And as Ry points out they have no clue as to how tracers actually work.
I uploaded one called “Bulletproof Water” here:
http://www.recreationalexplosives.org/video/interesting/index.htm
They claimed that an Armor Piercing .50 BMG bullet will be stopped by a couple feet of water. I didn’t see the core in the pile of fragments Adam gathered; I find it hard to believe the core would disintegrate in water.
If the jacket came off then a lead core will turn into sand. But an AP round has a hardened steel core that won’t break up even when going through mild steel. Still, it was a very interesting episode. The 147 grain FMJ went through several feet of water but the .50 BMG only a few inches.