"All guns" aren't even necessary. All they have to do is get each gun owner in the registry, by any means. All it takes is having one firearm on record teling them which door to knock on. If you believe they will leave all your other firearms alone and only take the one listed on the registry... I've got some bad news for you.The have to get that registration of all guns in place first.
That's why compliance to any registration regulation in any form for any firearm is so dangerous. They'll all be scooped up in the same net. IE., Jumping on the pistol brace rule before absolutely necessary.
Make one known to the gooberment, you're ratting them all out.