If all guns were banned and a confiscation ensued, it would get really ugly.
Places like Austraillia and Britain were able to ban, because the citizenry are used to more government control in the first place, thus there was little push back.
In this country things would be quite different. It would go something like this:
The US government starts out by first ending the sales of all new guns and ammunition, and having a buyback program for all firearms that are already out there.
This buyback would go on for months, possibly years. There would be hundreds of thousands, or millions collected by the government during this period.
A date then would be announced that all firearms must be turned over to the government. The date would more than likely be months after the end of the buy back period, and any firearms collected during this period would NOT be paid for. During this period, the federal government would make it clear that any American found with a firearm after this final date would be immediately subject to federal prosecution.
Hundreds of thousands, or millions of more guns would be collected by the government during this period.
Since there are somewhere around 300 million firearms owned by private citizens, and since the Second Amendment is especially treasured by millions of Americans, there likely would still be tens of millions firearms in the hands of private citizens.
Now what ? Would the government literally go door to door to collect these firearms ? Would they be willing to do so knowing there would be blood shed on the streets of America by Americans ?
Would military, or police officers really be willing to fire on their neighbors and fellow citizens ?
Would other Americans tolerate seeing their neighbors killed or dragged off by the government ?
This isn't Europe, or Austrailia, millions of us wouldn't go down without a fight, it would be another civil war, and I don't think the government, or the majority of Americans have the stomach for such a thing.
