Less ammo. He would have only had a handgun with a few rounds. He would have expended some against the police. A hand gun probably wouldn't have deterred the police like the AR-15 did and they might have killed him sooner. Or, if he got in, less shots to shoot in the classroom equals less victims.
What @Chris Craig said. If you or I was going into a firefight or warzone, which would you rather have, an AR or a 9mm? There is one that is obviously more effective for defending yourself, or in this case "barricading yourself while murdering children". If the dude had a handgun I have no doubt the 19 officers would have gone in there earlier.
I don't know for sure exactly how they are getting in. Likely by knowing the code or getting keys. Finding keys seems to be the most likely. In Newtown he killed his mom and got the key to the safe where the big guns were kept. I personally had access to everything in my house growing up, even the stuff I wasn't supposed to. I never abused that privilege, but I could have very easily.
How is an AR more deadly in a close situation? The first thing I'd want is a hand gun. Far easier to pack, less obvious that you have it, easier to aim quickly... Definitely would prefer a hand gun in a building. If I'm trying to kill at distance I'd go for the AR. But that wasn't the situation. What makes you think an AR is be more deadly in a baracaded situation?
Most pistols sold in the US come with between 10 and 17 rounds. It takes about a half a second change a magazine with an afternoon of practice... I don't think this is as much of a factor as you think it is...
That's on your parents. Gun safes should be mandated to have passcode or combination locks. Or combo key/passcode/combination That itself would cut down on kids getting in safes. There are obviously some pretty shitty safes out there. Unlike the Newtown shooter, most are not going to have a gun to kill mom unless they get into the safe to get the gun.
Intimidation factor. A bigger gun with faster shooting ammo is going to deter police from getting close enough to take him out. A hand gun, police would be more likely to go after him.
It wasn't a close situation. That's what I'm saying. He was shooting at people from range, got himself into a barricade situation, then the officers wouldn't do anything.. If he had a handgun I don't think it would have been the same situation.
Not always. When I was a kid there weren't any. Took so long to load a musket that the teacher could just grab it away. barfo
Regardless, police need to press in that situation. That's how you save lives. There would be no further police life lost with an AR in that situation than a handgun.
Handgun bullets, although usually of a larger caliber, pack less energy than long barreled weapon bullets. In addition the AR-15 round is designed to tumble through the target causing more damage. Also, handguns are way less accurate at a distance.