Guess what, you can use a pellet gun for target practice too
and I do. I can use my pellet gun to kill things too. The primary purpose of my particular pellet gun is, as advertised, to kill animals, up to the size of a fox. That's approx. the same power as a .22 LR; I wouldn't doubt that a head shot would be lethal to a human.
And you said they were illegal in the state. So what, my point is they were purchased and registered legally so your argument that they're illegal in the state is stuff
According to the news, the rifles used in the shooting were legally "assault weapons." The guns were bought legally but then modified in such a way that they, according to california law, have been "manufactured" to fit the description of an "assault weapon"
"assault weapons" are banned in californiathe
"assault weapon" ban did not stop the criminals from using an "assault weapon" to murder