Better yet, declare a state of insurrection and order NG troops to arrest Compass, Nagin, et al.
Is it insurrection?
You don't even need to do that.
Confiscating the firearms of Americans is a violation of their civil Rights. It is a federal felony to violate (or even conspire to violate) an American's civil Rights under color of law. Federal law provides a 10 year sentence for each count.
Any federal agent could arrest them. Any federal prosecutor could charge them. Bush or Gonzales could fix this with a single phone call. As could any of those "pro 2nd amendment" folks Bush appointed to DOJ.
I'm not holding my breath.