policy
Recently aged out ( I hate the word "retired") with my outfit, which in recent months has just released its updated policy on firearms and ammo.
The NPS still allows an officers choice at academy, on calibers from 9mm, .40 and .45, and considers a rather wide range of bullet weights in each caliber as "approved" provided they are expanding projectiles, or designed to expand, and are of US manufacture. What issued ammo a ranger receives may depend largely on what the preferences are of the chief , asst. chief, or instructor who is doing the ordering at HQ. Price plays a role for certain. I am not aware of a prohibition keeping a ranger from purchasing a favored load, as long as it conforms to guidelines. Pistols are still SIG, with a model or two dropped, and a new model or two added. I've not seen the new policy with my own eyes, only conversations.
Keeping multiple calibers on hand is an administrative pain, but does enable the officer with a selection of ammo/hangun and fit, that builds confidence and ability, at least that was the logic as stated to me. As we work solo mostly, interchangeability between officers was not considered as an issue.
Personally, I think there is merit for larger caliber and heavier bullet in the LE handgun. LEO's are more likely to have to deal with barriers like auto glass, and anybody in a cold climate or outdoors may have to deal with heavyclothing, coats, vests, etc. In such instances, the heavier slug may do better. My observations on the job were that the 9mm was most often chosen by admin types and the less common caliber choice. There was about an even split on .40 and .45, the .40 a bit more popular due to capacity.
The hi cap .45's like the new P227, (approved) or the Glock 20 (as example) to me, would seem ideal to the shooter that could handle them, fit and performance wise.