What if there you shoot an intruder with a 10 round magazine. Do they search the whole home after something like that?
Locally in my area of western NY, they usually charge you if they find a 10+ round magazine or an unregistered semi-auto while investigating another crime. Usually when drugs or domestic violence is the reason for the call. They do not actively look for violations.
If you ever get arrested, they will put a photo of all of your weapons in the paper. One guy awhile back was arrested for drugs and in the collection of weapons they put in the paper had some muskets. I guess they were old school dealers. They also had a bb gun.