They'll succeed at first. No doubt about that. Then they'll start getting dead. This will evolve very quickly to the sort of 'ring of fire' that surrounded the British as they made their way back to Boston from Lexington. In fairly short order, it's going to be a risky proposition to roll your SWAT wagon down the street. We Americans are nothing if not fearless and inventive.
The lesson to the confiscators: stay home - stay alive.
Meanwhile it's going to be suit-hunting time. The lesson to the suits: tyranny is both expensive and fatal.
Alternatively, if someone wanted to send a message/make an example, with
1. Sandbags
2. Self-darkening welder’s helmet
3. Ear protection
4. Chemical weapons protection (gas mask, at a minimum)
5. “Uppers”
6. “Means of self-defense”
one would be an exceptionally tough nut to crack with anything short of a tank or helicopter gunship.