Flechette rifle

In the Hyperion universe based upon Dan Simmons' novels, the flechette rifle or pistol was loaded with "egg shaped" cartridges that, when fired, deployed into a cloud of several thousand hyper-velocity steel needles, in a manner similar to the discharge of a shotgun shell, though much more deadly and effective for longer range than a shotgun.

The flechette cloud was immensely lethal to targets within a hundred meters, though at that range and beyond, the natural spread of the shot rendered the weapon exponentially less effective. Within a radius of several dozen meters, the area impacted by flechettes would be pulverized by the sheer quantity of the needles and their collective kinetic energy -- sections of organic targets struck by portions of a flechette cloud would appear to disintegrate.

Flechettes lose effectiveness at ranges exceeding fifty to a hundred meters due to a loss in projectile velocity and accuracy; they are also less effective against armored targets, against which energy weapons are generally the preferred choice.