I'm not in LE or security, but I do have a few duty guns. I have a Colt Commander Lightweight that I bought from a retired cop and got his complete duty rig with it. Also bought a cops backup Walther PPK/S .380 with a IWB holster. His wife didn't like guns so he sold his backup piece which never made a lot of sense to me. Also have an older surplus FN High Power that was an Austrian Border Police duty gun. Wasn't looking for cop guns, these were just ones that happened to be duty guns that came my way.
My neighbor down the street works some very high end security and is issued an M-4 for his daily work. Not sure what his sidearm is. The township carries .45 Glocks, AR carbines, and 870s. They just switched from Benniles to the 870s because the whiner on the force said the Bennalis were too complicated. Sherrif's dept carries older HK 9mm, I forget what model, but they love em. City cops just changed from 9mm S&W Sigma and Ruger PC carbines (sombody didn't want to spend money} to I think Sigs in .40 and ARs. They do not carry shotguns anymore. One of the local cops recently used his AR with TAP rounds to shoot a loose buffalo calf 12 times that was running around town.