From what I read about the Sandy Hook shootings they were done with handguns. The AR-15 rifle was found in the shooters car.
So the .223 wasn’t used in the shootings.
Sometimes I read the exact opposite version of that scenario. Who knows why it is so hard to get the definitive information or why they are obscuring it.
That's assuming political people didn't get in there and rewrite everything to attribute the shootings to the Bushmaster, the "evil black gun" ..... oh, and someone mentioned in here, another, related thread, that the weapon found in the trunk of the car was actually a shotgun. (Something like a Saiga maybe, that takes box magazines and has a family resemblance to an AK or a Dragunov.)