Those look like M-4 or a variant (
@Dr. Dwayne ?). That would be a solid platform. Pistols are vastly more inaccurate at any distance.
Yeah that's the platform. Oddly they are a little bit long for what Simbo alluded to. Look like at least 20" barrels maybe even 24". Longer than what you'd like indoors. Shooter probably had a 16" because that's what most stock AR-15s are sold with. US Army mostly uses 14.5".
Just wondering if there's all that much difference in it, if the argument about waiting for better hardware holds up.
Ballistically it's a pretty even match. Cops edging a close contest on accuracy and muzzle velocity. Ergonomically and geometrically, shorter barrels have the advantage allowing for faster target acquisition and discharge.
Pistols and rifles are equals out to 15 yards or so. Pistols maybe having an advantage for those ergonomic and geometric factors noted above. Beyond 15 yards it's more difficult to maintain accuracy with a pistol for most people.
But for all of this, the cops had a numerical advantage and chose to protect their own lives for 40 minutes over those of the school children.