One important issue that hasn't been discussed.
Our very familiarity with firearms may lead us to make assumptions about the safety of the firearm that we assume others to make as well. We know the gun is unloaded or loaded with blanks. We know the gun is harmless as a result. BUT we make a dangerous mistake when we assume that everyone else should know what only we can know about that gun. Answering the door after being notified that the police are there while holding a weapon, even one we know is perfectly safe (even if it was a demilled drill rifle), is the beginning of a horrible mistake. The cops at the door have no way of knowing the weapon isn't loaded. They see the rifle with the bayonet on it and immediately react to the threat. We don't think of ourselves as being a threat, but the cops see the gun in our hands and can't assume anything else so they order us to drop the weapon as the first step in their training in how to deal with an armed individual. If we as the gunowner fail to recognize that they think we're a threat and we react in any other way but to comply with that order our familiarity and private knowledge can get us killed. Even with no bad intent our assumptions can be deadly.