Um... quick observation, has anyone answered the OP's question or just taken the whole thread down another path?
To respond to the OP, the only time I had to have my weapon ready was a few years ago, at 4 am, and someone was pounding on my door so hard it woke me up and it seemed like they were trying to get in. I came to the door with .45 Colt revolver in hand, yelled for the person on the other side to announce themselves. They failed to respond. I took a defensive position and slowly cracked open the door. Of all people to be pounding on someones door unnanounced at 4am, the local PD. The second I noticed I slowly put my weapon down, and they preceeded to tell me that my car had been stolen. Then proceeded to treat me like I stole my own car for insurance fraud.(Long story)
Shouldn't the police be announcing themselves when damn near breaking down someones door? They scared the crap out of me and my girlfriend and I believe they should have announced that they were PD, especially after I asked.