Summary

I am a huge fan of RedCowl's Nerf Rival Platypus conversion kit for the Nerf Rival Knockout. I love both the concept and the end product.

However, I found that the flow adapter from the original mod creates a poor seal with the plunger tube assembly, even with electrical tape. Additionally, the original adapter tends to leave a gap between itself and the Spring Thunder shells. This breaks compatibility with the Triple Rival Round Shell from Spring Thunder, as well as other high-crush/high-pressure shells.

To fix these issues, this flow adapter is longer and has a tighter diameter. It should fit perfectly over the original plunger tube assembly and O-ring without any electric tape. The output diameter is the same, and you can use the same O-ring as the original.

In my testing, I found that this adapter installs perfectly with some moderate force. You do have to be careful about making sure the original O-ring stays in place as you wiggle and slide on the new adapter. With the adapter, my Platypus now shoots the Triple Rival Round shell and Inline Clip shell from DaltonFam08 perfectly every time (after adjusting the position of the adapter slightly forward).

I recommend following the original suggested printing instructions and settings for the original flow adapter when printing this adapter. Those instructions should work perfectly fine.

Due to the fact that I'm rather terrible with Blender, I found that Cura 5.2.1 did flag the part as having extraneous surfaces, but I had no issues upon printing.

TLDR: This flow adapter for the Nerf Platypus creates a tighter air seal than the original, allowing for more FPS and ammo types. Some adjustment may be needed to get the best air seal. Use the printing instructions for the original adapter.

If you have any issues, leave a comment and I will do my best to respond.
I would love any and all feedback, as this is is my first upload to this site.