@BillRM,
That is incorrect. Assault rifles are capable of either full-auto fire or burst fire. The Virginia Tech shooter's guns were capable of neither.
Assault rifles provide effective fire at a 300 meter range. The Virginia Tech shooter's guns did not.
Long guns also create much more devastating wounds than handguns.
The fact that they were not revolvers is irrelevant given the fact that a bunch of revolvers could have provided the same rate of fire using New York reloads.