It's a long discussion...and I say "discussion"....with quite a bit of truth on both sides. Unfortunately a discussion usually degrades into a debate, with people on far opposite sides insisting their side is correct, and the other side is wrong.
But bear with me for a few minutes....
***First, we have to ask ourselves "What changed?" And when I say "changed"...I mean in society, and especially todays youth, in recent decades. First..when I grew up in the 60's and 70's, done with high school early 80's....where I grew up, we walked around with our rifles over our shoulders, going through the woods behind neighbors homes, walking down the street to other woods, going over friends houses where there were often hunting rifles right up on the living room walls, the old mans clear glass door gun cabinet in the living room. Neighbors never cared about the boys walking around squirrel hunting with our guns. If a cop drove by while we walked down the road with a rifle over our shoulder..they didn't care, sometimes a wave.
When I was in high school, we had a rifle team. Members of the rifle team could bring their guns to school, keep in their locker, take on the school bus.
It wasn't a problem! Kids weren't shooting up kids! We didn't shoot up the school. We didn't shoot out the school bus windows. We didn't shoot our neighbors homes.
....our fathers would have whooped our arses. And our neighbors would have whooped our arses too! But back in those days, there was this thing called "accountability" and "punishment". Not excuses like.."but he was a good kid". We were all told/taught to respect guns by our fathers, and the hammer of thor was brought down on us if we didn't.
***My next point. The AR-15 is not a recent invention. Came out in 1959. Was widely available in the mid 60's...it was available for sale to civilians in 1964. By the end of the 60's....Colt was selling quite a few to civilians each and every day...they were flying off the store shelves. How did we go for quite a few decades before having a problem with todays youth utilizing large capacity semi autos (like various ar-15 clones) in mass shootings?
...."What changed over recent decades?"
***We have had mass shootings that did not involve ar-15 types, such as, in 1966, the University of Texas tower shooting (15x dead)..the kid had a bunch of single shot rifles and pistols.
***If you look at "many" of the other mass shootings, the bad guy had a long, proven track record of problems. Now I know HIPAA laws prevent this from happening, but we MUST allow that to tie in with law enforcement, and the ability to "not" purchase firearms. If you go review the history of most mass school shooting bad guys, you'll documented history of mental problems, seeing psychiatrists, being on medication, prior problems with law enforcement, etc. We have to open the laws up to allow law enforcement to connect the dots. There are many situations where some homes just should not have guns in them. The Sandy Hook shooting (not far down the highway from me) is a classic example, that kids (Adam) mother was a gun hobbyist, she had a collection of guns, and ....despite many years of warnings....she paid the ultimate price (she was one of his first victims before he drove to the school).
***You can take the above point...and find many similar situations in other school shootings.
***While I grew up with guns in the house, and spent much of my youth shooting in the back yard, and at the gun range, and my father was a life long NRA member, and I am too, I am a firm believer that a carry permit is not a right, but a privilege. I need to earn it, and I need to maintain a law abiding, problem free life, to maintain it. If I turn out to be some cause of domestic violence, or start getting multiple arrests due to aggravated assaults or other violence related crimes....I'd expect my carry permit to be revoked in a hurry! I had no problem going through background investigations by local PD et all as part of my process in obtaining my carry permit, I'm totally comfortable with that.