This is a letter I sent to my armed guard students/clients in 2019:
My recommendation still stands.
Gentlemen I routinely get questions from my students concerning the type duty ammunition that is best for law enforcement and security work. I wanted to pass this along to you for your information and consideration.
There are a lot of opinions and marketing efforts out there but it makes sense to take advantage of the extensive testing and research the FBI has done before selecting duty ammunition for their own agents to carry.
The ammunition selected by the FBI is manufactured by Hornady. It is labeled Critical Duty. This is a Plus P ammunition that should only be used in modern firearms, and that you would not want to shoot a lot of for practice. But it is a very effective defensive round.
As a result of the research done by the FBI, we recommend Hornady Critical Duty.
For 9mm it is labeled Hornady 9mm Luger +P Flexlock 134 grain Critical Duty.
For 40 caliber it is labeled Hornady Hornady 40 S&W Flexlock 175 grain Critical Duty'
For 45 caliber it is labeled Hornady 45 ACP +P Flexlock 220 grain Critical Duty
I also often get questions about how often duty ammunition should be replaced. Shelf life of ammunition that is kept in climate-controlled space is essentially unlimited. The ammo we carry around with us every day is another matter.
We are in a very humid climate and humidity affects the duty ammunition we carry over time. Whatever climate conditions you are subjected to, so is your firearm and ammunition. Although modern ammo is pretty durable, we recommend that duty ammo be replaced at least once per year, and preferably every six months. It is a good idea to shoot the duty ammo for practice or qualification and then replace it with new ammo.