To bring it in line with FNV's multiple ammo types, have you guys considered making alternate dart ammo types? The dartgun seems especially suited for that. The recipes could be fairly similar, something like...
1x Dart
1x Empty Syringe
1x Drug or Poison
...with a script similar to the coinshot script to occasionally leave darts and empty syringes on people you hit. Unmodified darts could just do piddly little damage. Radscorpion venom could make the regular legcrippling darts, with bark scorpion and cazadors having similar, but different effects. All those weird tribal venoms I've never gotten around to using like Bleak Venom and Mushroom Cloud could have the real devastating effects. A doubleshot of Med-X could make a good tranquiliser dart. Corrisive materials like fission batteries or Abraxo could make standard damage+ darts. A couple units of flamerfuel and an energy cell could make an incendiary dart.
I know it might be out of TTW's scope, but considering FNV got ammolists for each caliber it seems kind of fitting that the dartgun at least (probably not the railway rifle, though) should have a variety of ammo available to it.