Holy heck, where do these Parker’s live that they have to register their firearms? Basically, the cops can do whatever they want, and recourse comes after the fact. Unless, possibly, you know your rights, have a camera and a witness, and you don’t open the door. They would have to have probable cause that a felony has been committed. Others more knowledgeable than i , and that’s a lot, will feel free to correct me.
I don’t think an anonymous call from a neighbor would support probable cause for a warrant, so why should it support probable cause to believe that a crime is being committed and that exigent circumstances exist? Police can go to the door and inquire of whoever answers, and listen and look for signs of distress, but in my opinion, they cannot barge in without a warrant. But that was the old America; nowadays, they have the TSA stopping people at rail stations and on city streets, drones in the sky and cameras recording license plates at every corner. Those old rules and rights are becoming quaint.