Tonight, my son and I went out to the back yard to shoot some stuff.
We set up the targets, and walked back up the hill. He loaded the gun (Ruger 10/22), cocked it, sighted for a moment, then, without taking his finger off the trigger, went to set the gun down. As he did this, the weapon discharged. I immediately declared him "off range" and took the gun, cleared the chamber and told him he was done for the day, after only 1 shot. He claimed that the trigger had stuck and he was going to ask me to see what was wrong.
Well, there was a lot of hysterics as only an 8 year old boy's sense of injustice can bring out, and I yelled and he cried and the guns went away.

Later, after dinner, I spoke with my wife on the subject, and she asked why with every other skill, when you make a mistake, you try again, but when it comes to the rifle range, I am such a hardass and put a stop to the shooting. As an aside, we had something like this happen once before, when he picked up his (unloaded) gun at the gun club range while someone was downrange setting targets, and I shut things down immediately then. I suggested that when you fall off a bicycle, nobody else can be killed or injured, but with guns it's different. She pointed out that we set up a rifle range here with a berm, backstop and other safety measures, and if he can't make a mistake there, how will he learn how to avoid mistakes in the future when it really matters, like when he's hunting with me?

Well, my son and I spoke for a while on the subject and we came up with an agreed-upon compromise. It was mostly his idea.

You start with three "stars". Minor safety violations, you lose one star. Less minor, you lose two stars, Major violations you lose all three stars at once. We agreed that an "accidental discharge" downrange, when the range was clear and you were intending to shoot is worth 2 stars, but firing downrange at any time when the range safety officer has called "cease fire" is a three star violation.

I'm trying to define a general, objective list of one, two and three star violations, and I came up with the following (for which I ask your comments)

1 Star:
- Any safety violation which could create an unsafe situation (e.g failing to check for an empty chamber, failing to check for clearance from others on the range when going down range during a cease-fire, leaving an unfired or mis-fired round on the ground)

2 Stars
An unsafe action that may or may not involve the discharge of the weapon downrange into the target zone. Examples include failing to keep a weapon with a chambered round pointed downrange, discharging a weapon without maintaining control of the weapon (e.g. firing without sighting, firing "blind")

3 Stars
Failing to cease fire when ordered.
Discharging a weapon at anything other than a target
Pointing a weapon (loaded or unloaded) at any person at any time.
Going downrange before a sease-fire is called.
Killing the family dog or cat