These will help you brass your Nerf Knockout for half-length darts. The 17/32 brass piece friction fits into the "KOB_Adapter_1732" which friction fits into the stock Knockout with air restrictor ripped out.
The KOM_L and KOM_R are a split barrel that can be used to nest the brass together, may need some sanding and/or electrical tape to get the right fit for 9/16 brass.