"Most capable of killing" doesn't mean anything though. A bullet is a bullet is a bullet. What gun its fired out of doesn't really matter when its against soft targets. 9mm 5.56 and 7.62 are all the same lethality.

Edit: Also comparing the use case of gangers and even school shooters with soldiers is foolish. The main benefits of a rifle (in war) are range, stability and higher cyclic rate. Virtually all rifles are semi automatic so cyclic rate doesn't matter. And at the range pretty much all school shootings take place in, pistol vs rifle doesn't matter. Stability is also largely irrelevant based on distance and the fact that unarmed civilians dont shoot back.

All this to say, 91% of school shootings are perpetrated with pistols. So this hyperfixation on "assault rifles" is silly. I say again, you've been lied to.