Wrong as usual. A 5.56 is a smaller bullet and a smaller diameter cartridge.
9mm and AR mags aren't interchangeable. I don't know if you knew this or not.
The only talk that's coming from is your preferred news media.
Stop trying to sound like you know what you're talking about. Mags can be bought for either with a full range of capacities.
Obviously you don't understand the topic being discussed. It's about putting an offensive weapon in the hands of a disturbed individual which in turn gives that person a twisted sense of empowerment to bring a violent end to a condition that individual believes. to be unjust.
Now this past Friday a kid who had been expelled from his high school in western Pa was discovered back in the building and was caught along with his pal setting up plans for what was described as a Columbine style mass shooting. Luckily a student saw him there walking the hallways, contracted her mother who in turn called the school Police FBI and DHS all responded. The kids were detained , jailed and when authorities went to the kids home they found the usual arsenal of AR's AK's shotguns and a huge store of ammunition. Both 17 the question will be if they lived with their parents. It would appear that they believed that they had a score to settle . Didn't matter who they killed as long as they killed as many as they could.
BTW. They were both jailed and will be tried as adults on a slew for federal charges. Hopefully their legal guardians will be held accountable as well.