Sort of like a shotgun. Part of what made flechettes so effctive is that the explosive charge seperating the flechettes was too powerful, twisting them into random chunks of metal. This coincidentally caused much more damage (although with not quite as much range) than the intended darts acting as darts. Dont ask me where I got this, but it sounds right... something about calibres and whatnot... right. what it boils down to is that the flechettes are less effective making neat little holes in something than ripping nasty lacerations into it. Not that many flechettes will hit an individual target unless well-aimed with a very close range blast, so they are generally used as an area-suppression weapon (Vietnam War) However, in the narrow corridors of ship-to-ship, a smaller flechette gun with a smaller blast cone would be quite effective (literally shredding the target as mentioned) although to get this power in a recoilless gun the backblast would be even more lethal to people behind you than the shell in front. (the danger zone for 3rd degree burns in the Vietnam era 120mm guns was something like a quarter mile). Fun things though, and Marathon Infinity used flechettes in a SMG (theoretically they would have better armor piercing qualities also)
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You deal death with your roars and your screams, your threats, your taunts, your overblown ego. I hand it out, one with the steel and the silence, the blackness around me, with a thought.