It was forgotten. Just like the 3rd amendment was.
People kept buying guns, but everyone sort of assumed (and rightly so) that the government could ban guns.
Hell, the shoot out at the O.K. Corral was over gun control, and the Cowboys gang was clearly in the wrong, and all of them were wanted criminals before the shootout.
But more to the point, the gun ban for Tombstone, Arizona was completely legal.
All of that is while militias still technically existed. After 1903, militias did not. Which is why the National Firearms Act of 1934 was ruled fully constitutional.
And that was the final word on the 2nd amendment until a convicted murderer in partnership with gun manufacturers decided that guns for everyone should be the goal of the NRA.