I'd say a lot depends on why the cops are there, and the individual cops. If they are there because someone who lives in the home is suspected of a crime, having an illegal weapon in plain view can be a problem (and grounds for an arrest). Same if they are visiting you because of a complaint from someone, like a neighbor. The cops don't know you, they don't know if you're a good person. But if they see that you are in possession of an illegal weapon, they might very well form an impression of you that you would not want. The simple fact is, if you are in possession of an illegal weapon, that weapon is a ticket to a jail cell. That ticket might never get punched, but it's always there, and it always has the potential to send you to jail. All cops are different. Obviously encountering the wrong cop on the wrong day can be a problem under any circumstances. But even if a particular cop is "cool", my advice is to never expect a cop to turn a blind eye to a violation of the law. Even a "cool" cop might take issue with a clear violation of the law, especially when the violation involves a weapon. But even under the best of circumstances, if the cops enter your home, and they see a weapon that is illegal to possess in your state, they might, at the very least, confiscate it, and legally so. A cop has to worry about their own liability. If they know someone is in possession of an illegal weapon, and they don't do anything about it, and the person later kills someone with that weapon, that could be a serious problem for that cop. And if an illegal item gets confiscated, and if it's worth a lot of money, or cost you a lot of money, or has great sentimental value, then you're screwed, because you have no recourse to get it back.