Gary Jackson never stood a chance.

Gary was 28 and working as a security guard at a taco truck in Oakland, Calif., in 2009 when he saw Dreshawn Lee carrying a sawed-off shotgun and reported it to police. Three months later, Lee took his revenge by shooting and killing Jackson with an AK-47-style semiautomatic assault rifle.

I was the prosecutor who persuaded a jury to convict Lee and persuaded a judge to put him away for 65 years to life. But Gary’s autopsy report still haunts me.

Trauma surgeons and coroners will tell you the high-velocity bullet fired from a military-style, semiautomatic assault weapon moves almost three times as fast as a 9mm handgun bullet, delivering far more energy. The bullets create cavities through the victim, wrecking a wider swath of tissue, organs and blood vessels. And a low-recoil weapon with a higher-capacity magazine means more of these deadlier bullets can be fired accurately and quickly without reloading.