As a final thought, I see above where someone felt that Selleck's reaction was not the proper manner in which to instruct or discipline one of his Employees.
The extra on the set was certainly not an employee of Tom Selleck's. He was an independent contractor, hired on an hourly basis, by the production company.
And in reality, when safety is concerned, it doesn't matter who works for whom. It would have been totally appropriate for a janitor on the stage to set down his broom, grab this guy by the collar, and read him the riot act.
By the way, I'm guessing that sometime during our youths, we accidently pointed a firearm in an unsafe direction and were immediately and loudly chastised or disciplined by our fathers or other family members, or maybe by a Drill Instructor. None of us are crying about it,and we are glad that we were corrected.