How I'd react would depend on the situation. Some clown without a warrant will get a "What firearms, officer? You want to come in to look around? May I see a warrant? Well, you go get a warrant and come on back." sort of response. If they force their way in, they keep what they can find.
Immediately after (or during, if possible) such an encounter, I would be on the phone to friends and family warning them what's going on.
If possible, DO NOT keep all of your firearms and ammo in your home. Stash something away for a rainy day.
The follow-up question I have is this: What would you do after this particular bravo sierra went down?