"I'm talking about accidental shootings."
What is an "accidental" shooting?
How accidental is it if somebody takes a pistol out of a drawer, flips off the safety, loads it, charges it, aims it at his friend, and pulls the trigger?
I don't care how old the perpetrator is--it is a deliberate, specific action. There's no "accident" involved. "Accident" is a word which, unfortunately, suffers from gross mis-use these days.
This is why age is important. If you're talking about a pre-school child, they don't have the level of mental development to be culpable for their actions. A teenager does (usually). These sorts of things need to be reviewed on a case-by-case basis, which incedentally is why we have a juvenile justice system.
Your stated idea of negligence seems rigid irregardless of the child's age. However that interpretation is incorrect. It's pretty negligent for a parent to leave an 18-month-old baby home alone for a couple of hours, but is completely acceptable to trust your 16-year-old alone for the afternoon.
Let me put it this way--the GUN isn't the issue. The kid's level of mental culpability is the issue. If you sit a baby on the edge of a filled bathtub then go into the other room to talk on the phone and the baby drowns....are you going to be liable? You bet! However, if your 14-year-old manages to drown in the tub, then usually that wouldn't be negligence. As children age, although they're still treated as minors under the law, they also become more accountable for their own actions.
J_A_B