The device itself consists of a clear plastic “docking station” that slides on to the end of the gun, and the projectile, which looks roughly like a clown’s nose.
When the officer feels the need to discharge the projectile, he squeezes the trigger on the live round in the chamber, which travels down the barrel, smashes into the back of the projectile, and then continues downrange embedded in the projectile, which is supposed to strike the threat with enough force to put him on the ground, but won’t (hopefully) kill him.
In other words, this device takes a reasonably efficient kinetic energy weapon and converts it into a distinctly less efficient kinetic energy weapon. By blocking the muzzle. Now, I’m no gunsmith, but that doesn’t sound like a very smart idea… especially since you can’t make a firearm ‘safe’ to use on other people. Physics has the final vote; and it is the consensus of physics that when you throw a physical object at another object at very high speeds, there’s going to be a reaction at the point of impact. In other words: if you’re knocking somebody down, you’re running a real risk that you’re also going to mess that person up.
I understand that people don’t always want to face this, but a gun is a thing that kills. Don’t carry one outside of a target range if you can’t make your peace with that. And for the love of God, don’t make a cop wear a clown nose on his gun, either.