Mr. Nugent is referring of course to "black rifles," a particularly deadly strain of automatic assault weapon made specifically for close combat. And perfect for classroom mayhem.
What is so telling in the NY Times full story is that no matter what legislators may try to do to curb the sale of such arsenal, Americans always find a way to keep buying and arming.
If you Google "AR-15," you get 1,590,000 entries in 0.21 seconds, which shows there is some interest in this madness.
Read the article and lock the door.