like marbles on glass
So you don't know how much easier it is to be fast and accurate with a rifle compared with a handgun.
I know, from his account you posted, which I watched most of, but not all, that when he took up position he was about 20 yards away, which is within effective range for a handgun. I know also that when he and the driver who chased the killer caught up to the killer who had had crashed his vehicle, he was able to lay that rifle on the hood of the truck. Definite plus there.
I'm not saying he made a bad choice. At all. I'm saying it wasn't the only choice *for most people in most situations* because most people are carrying handguns in public, not rifles - which is in response to your false dilemma: that there was no choice between an AR 15 and "harsh language." You're making it sound like only an AR 15 could've worked in this situation. He was lucky, he was at home, where his AR 15 was. Unless he carried it with him everywhere, even into church, in which case I'd concede the point, but if he'd been sitting in one of the pews in that church that Sunday, it's pretty likely he would've had a handgun on him if anything. And I'm sure, given the salt of the earth kind of man he seems to be, if he'd had a handgun only, he would've gone after the killer the same. The guy is a hero.
To teach how to properly use rifles.