Premier Date: March 31, 2010
During their small scale tests, the Mythbusters discovered that water can diminish the force of a shockwave caused by an explosion, giving credence to this myth. For their full scale test, the Mythbusters hung rupture discs 5 feet above water, 5 feet below water, and 10 feet below water at 5, 10, 20, and 50 foot intervals away from the explosives. They detonated 50 pounds of three different types of explosives above the water: gasoline, ammonium nitrate, and dynamite. While the gasoline could only rupture the closest above water disc, the ammonium nitrate ruptured every single disc and the dynamite ruptured all the discs except for the underwater discs located 50 feet away. With these differing results, the Mythbusters declared that the myth was plausible, depending on the explosive.
The Build team filled several car doors with phone books and fired various firearms at it. The phonebooks were able to stop 9mm, .357 magnum, and .45 caliber rounds. However, the more powerful deer slug shotgun rounds and the M14 assault rifle were able to pierce the door and the phonebooks easily. Since the phonebooks could not stop all of the bullets, the myth was declared busted. However, the Build Team continued the experiment to see how many phone books behind the door would be needed to stop a deer slug and rifle round and found that only two phonebooks were needed.
The Build Team calculated how many phone books would be needed to completely bulletproof the car, which was around 900. However, this may phone books weighed significantly more than the car could carry, so the Build Team was forced to cut back the amount of phone books to 400. They installed a remote control system in the car and placed inflatable dummies inside to simulate people. For their first test, they drove the car around as they fired M14 and deer slug rounds at it. All of the dummies inside the car survived this test. In their second test, the Build Team fired various automatic assault rifles at the car, and all of the dummies still survived. For the third test, the Build Team fired various high powered sniper rifles at the car. Kari managed to disable the car with a .50 caliber round and the combined sniper fire managed to kill all of the dummies. Though the car was highly resistant to bullets, the fact that they could still penetrate the car and harm the people inside led the Build Team to declare the myth busted.