Advice on hiring your movie set armorer, by Steve Sailer ...
That's why rig for dive is checked by two people on a submarine. The producer, director, actor, armorer (maybe even the DP, who died) all were participating on a set that had a poor safety culture (e.g. the previous misfires). That ended up biting them in the ass. If you go to being "single point safe", when that point fails the system ...