Thanks.
From reading more about the guns, it seems I should not have used the (often abused) term assault rifle. The press probably wants to call a gun an "assault rifle", just because it looks big and menacing. Whereas, things like if the gun supports fully automatic mode (and maybe burst fire mode), and other military weapon features, are probably more important.
Apparently the term "assault rifle" (which maybe should be called "assault weapon", anyway), has been so abused. That it is difficult to get agreement as to what it really does and should mean.
It seems I should never have brought up the AR-15 part of this discussion, and just stuck to the fact that a legal gun holder, while at their (or their parents) home, shot and killed some home intruders. Who apparently came equipped for a fight.
After watching that video. Apparently there have been a lot of house burglaries in that area, and they may have all been done by these four home invading crime team. If that turns out to be true (the Police are not sure yet), I will have even less sympathy for the criminals.