Weak reference indeed! Why, I'll have you know that came straight from the hit movie "US Marshals" starring Tommy Lee Jones and Drug Addled Has-been!
Seriously, before you have to search and replace five hundred instances of "Sig P228" with "Glock 19", you might give the agency in question a phone call. Their public relations department - and they will have one, will most likely be glad to give you that kind of information. You might even be able to talk them into a visit/tour/ride-along. It never hurts to ask.
If you want to use your own made-up TLA for your story though, it looks like Sig P228 would be the most likely casting for an issue sidearm. Unless you have definite plans to sell the movie rights to your story. Then you should issue your fictional agents the Desert Eagle .50AE in Hard Chrome as a Duty pistol, and a GE Minigun for a BUG.
Good luck on your story!