Recently, police have been involved in what looks like murder in the course of home invasion and murder with intimidation of witnesses and press. At this rate, I expect the distinction between the ordinary Ordnungspolizei and Einsatzgruppen to become insignificant.
As the experience with Minneapolis home invaders indicates, birdshot is not sufficient against armored opponents. At least two good hits were scored by the defender with minimal effect. The perpetrators were decorated by the police department even though they wrongdoing and settled the case at the cost to the taxpayers of over $600K. At least in this case the victims were not injured.
Jose Guerena’s example suggests also that holding fire is the wrong thing to do if attacked by either freelance or government thugs. A lawful person who has no cause to expect a police raid is more likely to face regular criminals impersonating police than uniformed criminals representing themselves. In any case, return fire at least spoils the aim of the invaders. Just kneeling before the intruders while they take aim or kill your pets is not the way to go.