Flechette Blaster
Flechette Blasters are a type of weapon used by Adeptus Mechanicus Skitarii. A very interesting weapon, it occupies its own unique little page as it is neither a Stubber (The ammunition and firing mechanism is too advanced and expensive to be considered Stubber category) nor is it an Autogun (it does not fire single solid slugs and its ammunition is way too specialized). A lightweight but lethal firearm, it is the favoured tool of Sicarian Infiltrators. This silenced weapon fires hundreds of tiny darts, each of which bears a dormant cell awakened in the gun's chamber. Where one dart hits, it emits a homing beacon that attracts others, resulting in a series of impacts that burrow through bone.
In terms of tabletop, these nasty little pistols are available on the Infiltrators paired with a Taser Goad. It's got rather low strength at S3, but 5 (FIVE!) shots means it packs almost as much punch as a rapid-firing bolter, while being fireable in melee. Overall, it is a rather meh weapon that obviously suffers against enemy with decent armour. So stay clear from MEQs and above.