With the one-note chorus in full song, we are again treated to the phrase "the easy availability of guns", with the subtext being that if guns were somehow less easily available, Things Like This wouldn't happen.
I've said it before and I'm going to say it again: Never in the history of our republic have guns been more difficult to purchase. Prior to 1968 they could be purchased through the mail. Between 1968 and 1993, all you needed to do was sign a form, in pink crayon if you felt like it, saying you weren't a junkie, commie spy, or crazy, and you took your gun home with no questions asked. The background check didn't appear until the passage of the Brady Law in 1993.
Name a mass shooting that occurred before 1968. How many between 1969 and 1993? How about 1994 and beyond? Folks, whatever the causative variable is here, it is not the ease of purchasing a firearm. If you want to play the statistics game, mass shootings in this country have trended upwards in lockstep with the difficulty of purchasing firearms. Am I suggesting that is the cause? No, but it makes every bit as much sense (or not) as the old "easy availability of guns" saw. Go find another bus to ride, because this one isn't going to your stop.