A nice idea if the liberals were rational.
When, not if, this “experiment fails, the immediate response from the liberals will be “We failed to account for ... Therefore we need to make it more restrictive and try again.” And again, and again...
Proof of statement?
Look at the great gay marriage “discussion”. How many times did Proposition 8 fail in California before it passed?
And when it finally passed that closed the issue and more discussion was prohibited since it was a closed issue. What? The three (or was if four) previous failures didn’t count once the approved answer was achieved?
Yes, indeed. If lieberals were rational, they’d propose an amendment to the Constitution to abolish the 2nd amendment. Then, after a few years, when it becomes apparent it is not going to pass or be ratified, should they still be rational, they’d drop the idea, and accept the second amendment to the Constitution. It would become the “closed issue” you speak of.
But, alas, they are not rational.