Does the GOOD GUY WITH A GUN actually work - NO. SAYS THE FORENSICS SCIENTIST

https://medium.com/@hollyefisherdexter/what-i-learned-about-the-good-guy-with-a-gun-theory-from-a-ballistics-and-firearms-expert-f7b695565369#.nozqq6223

 I spent most of that time asking questions of the Forensic Scientist who was an expert in ballistics and firearms. I learned a lot about guns that day, including these little-known facts:

• A bullet cannot penetrate through more than 3 feet of water (so if you’re ever being pursued by a shooter, jump in a pool or lake if possible).
• 3D printed guns are not a big concern for law enforcement at this time. It takes 40,000 pounds of external pressure to keep a bullet from exploding, which is why the barrel of a gun is made of steel. There is no polymer or plastic invented that can withstand that kind of pressure. What ends up happening with a 3D-printed gun is that the gun itself will shatter with one firing.
• Bullets can be traced to a crime gun due to microscopic impressions left on the bullet casing from the unique imperfections of the inside of the barrel of the gun.

But above all, the most interesting thing I learned that day was this: I asked about the “good guy with a gun” theory, and whether or not a civilian could have stopped the Aurora theater shooter. The forensic experts told me that sending civilians to do battle in a mass shooting would be a disaster. Police, who are highly trained and also experts in firearms, have an 18% accuracy rate for hitting their intended target in a live shooting situation. You can be the most expert sharpshooter at a shooting range, but add adrenaline, moving targets, poor lighting, emotion and chaos to the scenario, and all that training isn’t good for much. A recent article in Time Magazine explains what happens in the brain and body when shots are fired. “The brain stem sends out signals that cause blood vessels to constrict and hormones to surge…eyesight becomes narrower (literally tunnel vision) under such conditions. People who have been in gunfights describe hearing very little and perceive time slowing down. Amid this chaos, as police officers have to make difficult, split-second decisions, they can lose motor skills as the body reverts to basic fight or flight instincts.”

I’m going to assume here that if our highly trained police officers miss their targets 82% of the time, Joe Shmoe, with his little-to-no training, is going to fare much worse,