Yeah, I got explosives ... in my pants!
Ha .... well they would only be able to do this to a small # of folks before they start getting pinged by folks who still have guns (and this should also include you because you don't store ALL your guns at one location, do you?)
You can get new guns...better guns...bigger guns and now you would be a pissed off guy with a reason to use your guns. Or start making chemical or biological weapons ...
(Plus this is not the way it would be done ... it would be done Waco-style)