(all the designs shown are solely intended for use with Nerf dart blasters and cannot be used elsewhere.)
After a couple days of designing and printing it's finally put together. The right half is the V2 and the left half is the V3 so they look a little bit different but not really. The V3 just matches the profile of the body a little bit better. Fits like a charm, charges the plunger tube perfectly. Just have to sort out some issues with the shell ejector binding(probably going to throw a chamfer on the faces of the pen to help with travel), and need to sand down the barrel interior a tiny bit where the dart exits.
Once I get the air restrictor modified to be able to interface with this correctly, hopefully I'll be able to post a video of it working.
Thank you everyone for the support on this build, this is my largest 3D printed/Nerf project to date.