How?
Most firms I have dealt with have some rather strict requirements. Not saying they attract the best people, but they do have to insure their people are able to legally carry guns (if that is required).
Or do you mean “Security Firm” as in “PMC” or “Mercs”. Then they have rather loser requirements. One of these days, we are going to regret the building of private armies.
Signal 88 Security, a (franchise?) guard and patrol operating in Anchorage.