The Rules apply to cannons too.

A firearms instructor and collector was unloading a 40mm cannon from his SUV when it accidentally discharged and fatally struck him at his home in New Zealand.

Rule 1: ALL guns are ALWAYS loaded.
Rule 2: NEVER let the muzzle cover anything which you are not willing to destroy.

A power outage affecting approximately 8,500 customers in Westmoreland County, PA, was caused by an 18-year-old man who was target shooting with a rifle near a West Penn Power substation. The man fired a round from a rifle at his target, and the bullet traveled through the target, skipped off of the ground and impacted a West Penn Power pole and struck a 750 MCM distribution feeder cable which caused the pole to catch on fire. As a result of this event, additional damage was caused to the adjacent power substation, which caused a major power outage, according to the police report. I bet you couldn’t do that if you tried.

That’s Rule 4: Always be sure of your target, and what’s beyond it.

We have a report that a Las Vegas man was killed at a remote desert shooting range this week after his bullet ricocheted back and struck him. Rule 4 again.