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How the Taser Shotgun Shell Works

Firing the Taser XREP
The three stages of the XREP
The three stages of the XREP
Ethan Miller/Getty Images

A group of prison guards face the worst case scenario -- a full-blown prison riot. The inmates pose a danger to one another and to the personnel working at the prison. The guards hope to use non-lethal force to end the riot early and spare human lives. Using shotguns loaded with XREP shells, they take aim at rioting prisoners and fire. What happens next?

Upon firing an XREP shell, the small charge in the shell activates, propelling the projectile down the barrel of the shotgun. A ripcord connecting the projectile to the shell goes taut and then breaks. This activates the projectile's battery, and 20 seconds of high-voltage charge begins to flow through the device.

As the projectile clears the end of the shotgun's barrel, three spring-loaded fins deploy at its base. The fins cause the projectile to spin in flight, stabilizing its path. The projectile will spin even if the officer uses a smooth-bore shotgun.

Once the projectile makes contact with the target, several things happen in sequence. First, the four electrodes pierce the clothing and skin of the subject. Next, the impact causes a series of fracture pins to break. The fracture pins hold the nose to the base of the projectile. Once the pins break, the base of the projectile swings free of the nose. But it's still connected to the nose through two Kevlar-coated wires.

As the base of the projectile falls free, six Cholla electrodes unfold. The electrodes take their name from the Cholla cactus, which has barbed spines. If the Cholla electrodes pierce the subject's clothing and make contact with the skin, the microprocessor in the XREP channels electricity through both the nose and Cholla electrodes. This spreads the NMI effect over a larger area of the subject's body.

Taser's Web site says that most people tend to react the same way after suffering a blunt impact: They instinctively reach for the impact site. That's not such a great idea with the XREP. If the subject's hand makes contact with the XREP's reflex engagement electrodes, the microprocessor in the XREP diverts electricity and creates a circuit. Electricity flows from the electrodes into the subject's body and out through the hand that is touching the XREP. This spreads the effect of the XREP through more of the subject's body.

If the only contact with the subject is through the nose of the XREP, the microprocessor directs all pulses through those electrodes. That means a smaller area on the subject's body will be subject to the NMI effect.

The 20 seconds of voltage emission allows the officer time to close the distance to the subject and restrain him or her. But the shotgun shell form factor also means the officer can load a second round into the gun and fire at another subject if necessary.

What happens physiologically when you're hit by a device like the XREP?