Editorial: "cop killer" bullets

Note: this is an editorial about supposedly armor piercing "cop killer" bullets. Not a "how to" manual for killing law enforcement officers

Question: How do cop killer bullets work?
Answer:They don't

Cop Killer Bullet, this is one of those meaningless buzz words that gets used in movies and TV, it ranks up there with "silencer" and "Bullet proof vest" among weapons related misnomers. I give the media a free pass for referring to AR15's as an "assault weapon" on the grounds that they are marketed by there manufactures as being identical to what the military uses. Cop Killer Bullets, on the other hand were invented by the media and perpetuated by lazy reporting.

Armor piercing bullets are real, they are even produced for handguns. However, handgun bullets designed to penetrate body armor are not legal to sell to civilians in the US. Some types of hardened bullets were coated with Teflon to reduce friction inside the barrel. Black, Teflon coated bullets became synonymous with armor piercing rounds, and a line of black (but not Teflon coated) bullets called "Black Talons" where dubbed "cop killer bullets."

Although I've never tested black talons personally (I don't want to pay a 500% mark up to confirm what multiple youtube videos have already confirmed) I have done lots of testing with different types of ammunition and found some do penetrate certain types of body armor. When you get down to it, I've tested 9 different types of ballistic fiber, and determined that some bullets will penetrate some types of body armor.

The general characteristics that effect a bullets ability to penetrate body armor are

These are deformed bullets I took out of body armor test samples.
Most of these principles are fairly straight forward and logical, but when you deal with conflicting variables, the general results are as follows Given the wide variations in the constructions and materials of police/civilian body armor, I can't definitively say any bullet is capable of penetrating body armor. What I can say is something along the lines of "During X period of time, vests were made of X material, and could be penetrated by X bullet." It is also worth noting that I have shot the Infamous FiveSeven pistol, loaded with 45 grain Vmax rounds, into a 3A ballistic panel taken from a second generation Interceptor OTV. It did stop the round, but the sample was hanging, so I can't conclusively say it wouldn't penetrate with a harder backing.

All that said, it is actually pretty easy to penetrate even a level 3A ballistic vest. Any of the following would suffice