There is no good name for what I built but I love it anyways. It is an attachment for the tactical rail made out of a CS cartrige (recon, longshot, deploy) that stores darts (up to six) on your gun but can eject them at an enemy in a quick situation (you don't have time to reload).
Step 1: Rip Off Tabs
Get pliers and tear off the little curved tabs that keep the darts in the cartrige.
Step 2: Drill
Drill through the bottom right of the Cartrige (bottom left on the side without screws), going all the way through.
Step 3: Insert Peg
push the bar that holds the darts down. slip a toothpick or something skinny through the hole and over the bar.
Step 4: Finishing
Hot glue the tactical rail piece from any attachment you don't want (recon sight) onto the side of the dart holder. pull the toothpick out to jettison the darts all at once.