It's not the number of guns. That will always be a strawman for this country, because we have many, many, many law-abiding, sane people who just love guns. They'll never shoot another human in their lives, with any of their guns. All the other developed countries don't have those kinds of people, mostly. We're unique in that regard, but that in of itself shouldn't matter.Let's add more guns and make them easier to acquire.
The folks doing these mass shootings don't have to steal them for anyone else. They can walk into a gun store, or show, or go online, get a gun, easy, and then do horrible things.
It's 100% about how to make it more difficult to acquire or maintain possession if you do lose your grip on sanity.