One of the best electronic gun forums for collectors and enthusiasts is www.smith-wessonforum.com. It was there that I found this artifact of the past: https://smith-wessonforum.com/threads/us-post-office-revolver-methods-handbook.788619/ .
You will find a US Postal Service manual there, from circa 1967 according to the original poster, showing USPS personnel how to handle revolvers. To this day, postal inspectors are armed. In the past, it was common for some letter carriers to be issued .38 or .45 caliber revolvers to protect the mail.
Things were different then. When holding a suspect at gunpoint, the manual said “…you must be ready to shoot, with finger firmly on trigger.” (Emphasis theirs.)
Today, of course, we know better. My own take on it can be found here, on my new Facts and Firearms YouTube channel.
The same manual said that if the bad guy grabs at your gun you should clout him over the head with it or drive the muzzle into him hard. The manual was written a few years before Jim Lindell at the Kansas City Regional Police Academy came up with the Handgun Retention system that has saved so many lives since.
We’ve come a long way, indeed.