First I have allways been against "no Knock Laws"
Second from news reports there is an increasing number of fake police raids as part of home invasion robberies.
Thirdly it has allways been a part of my security plan to allways call 911 as soon as possible. My home is layered so as to require battering multiple doors to reach the occupied portion of the home.
If in doubt ask the dispatcher if a raid is ongoing at that location. In a small rural county such as mine dispatch should be able to respond. The call would go something like this:
Someone is busting in my door screaming police. I do not see any uniforms are you raiding (give address). Hurry I am afraid and armed. If the answer is yes we are raiding tell her that you have disarmed and am coming out. Of course if the answer is no start shooting.