The clowns on the Dallas City Council passed a no-smoking ban in the city. It is obeyed in roughly the same proportion as the speed limits. Now, restaurants that used to have smoking/non-smoking sections are all smoking all the time. I don't smoke, but when I smell tobacco smoke in a bar/restaurant in Dallas, it is the smell of freedom. There is some hope yet burning in the form of a Camel Unfiltered.
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Most LEOs & service members would comply and confiscate, even those who believe in RKBA. It would take more intestinal fortitude than most have to resist. Are they going to put their freedom, livilihood, and family on the line for some "gun nut?" Don't bet on it. No slam on LEOs, just a slam on current culture in USA, of which they are a part.
Some jurisdictions would not enforce such confiscation and would quickly find their LEO establishment replaced by "team players." You can always find folks to oppress their neighbors.
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As to what I'd do in the event...this ain't the forum to discuss such fun & games. I did, however, swear an oath to uphold and defend the Constitution from all its enemies. I don't recall anything on my DD214 releasing me from that oath.