Canberra, many of the US pilots are in the military.
Some, as I am, have also become part time police officers in addition to flying.
Sky Marshals have started showing up on some of my flights. At first they wouldn't talk about their armament, but some have showed me their clips........bullets appear to be .40 Cal, and are standard issue, no reduced charges.
When I was a cop we called them Black Talons. They are black painted hollowpoints that have grooves down the outside so they split into a star on entry.
Because of that, they grew notorious in the medical profession for the wound channels they create.
Then the color was dropped they were renamed Silvertips, and it's what most cops use today, although some cops have the first two rounds ball ammunition in case they have to shoot thru a car door.
Training will be required.
There is a humorous .wav file floating around about a cockpit pa describing how the crew is armed today. If anyone can tell me where I can post it for your consumption, I will.