That would never happen. The closest I could imagine is a national gun buyback program with the government giving substantial amounts of cash for each gun handed in. I think people would be surprised at just how many guns would be turned in for such a program.
Gun owners do not deserve handouts like this.
Tax payers should not be forced to pay off costs like this.
Take their guns away without payment. It is the only sensible way to do it.
Just compensation is a constitutional requirement.
Tell that to the slave owners.
Tho to be fair, if they hadn't started a war to keep slavery, they would have had to be compensated.