Under the heading of 'Making Pelosi and Feinstein and Schumer blanch

and possibly lose bladder control',
“All-time” means “in the 20 years they’ve been measuring this,” but still. In 1996, amid soaring public concern about crime, support for a ban stood at 57/42. Twenty years later, after a long period of stupendous decline in crime rates in many major cities, it stands at … 36/61. As recently as four years ago, the gap between support for a ban and opposition was still fairly narrow at 44/51. Four years later, the bottom has dropped out. Huh.
I strongly suspect a combination of
lack of trust in government,
seeing rioters run loose with cops doing nothing in some cities(see 'trust' above),
More and more people being exposed to the good gun culture in the US(Blazing Sword, for instance),
and seeing more and more information on places like Chicago, which have all the Bloomberg/Mommies/Obama-approved laws combined with horrible violent-crime rates.

The usual suspects won't like this at all.