Although we don't know where or how this young man got the gun he used, what law(s) do you think we should have that we don't have already, and how do you think those new laws would work to stop such access in actual practice?

"In actual practice" would be starting with one individual example of the 300+ million firearms, whether in private legal hands or a licensed dealer, and walking through the individual steps between that legal possession and this or any criminal misuse, showing how, in actual practice, that path would be physically interrupted by a given law.

Until the proponents of additional gun controls go beyond emotional rhetoric and generalized comparisons to other countries, they are not, and can not be, truly participating in good faith in the "dialogue" they claim to want.