“The Gun Within a Gun”

http://books.google.com/books?id=HCkKAAAAIAAJ

This must set some sort of record for aggressiveness — during World War I, Andrew Graham invented a shell that fires bullets. From Popular Science Monthly, February 1918:

The projectile is pierced with a dozen or so of rifled channels, each constituting a barrel loaded with a regulation rifle cartridge. … A shell like that which Mr. Graham has conceived can be timed to discharge its bullets efficiently, far from its target, unlike shrapnel. The bullets do not lose in velocity, thanks to their elongated form and their rotation. Their velocity is the sum of the shell’s velocity and their own.

Actually aiming the bullets, though, is another matter. “The firing can be timed so that at least one volley will scatter properly.”