I see your point with the AK, but it doesn't matter the situation, the first thing the police do is pull the nuke option. I don't know about other places, but officers in Reno have to wear body armor capable of stopping a bullet from their own weapon.
I'm sure the regulation is to stop a round from their own duty
handgun. The AK-47 7.62x39 round is not an especially high-powered cartridge, as rifle cartridges go, but just about any rifle cartridge will penetrate soft body armor. To stop rifles you need trauma plates, and trauma plates are too uncomfortable to wear all day, every day for regular patrol duty.