Umoya SuperBCAR

UPDATE: 20261002
I have been swamped with work and unfortunately haven't been able to dedicate the time to working on this project. However, my schedule has freed up and I should be able to get the final release version out by the end of the year. Some things to look forward to:

• Fixing an issue where some aftermarket (non-worker) barrels are too tight for for the standard collet. This mainly occurs with 3D print blaster kit barrels.

• Releasing 2 versions - a sub-220 FPS version and the regular 220+ FPS version. As with all barrel devices, YMMV, so splitting these into 2 variants will give the easiest time for the end user. 

• Refining the styling so it's less "tacticool" and more in line with the design aesthetics of many 3d printed blasters.

• Cleaning up the parametric file so it's more user friendly for customisation.

• Improved print geometry to make the overall experience better.

Introducing the Umoya, a customisable, printable Super BCAR.

Some backstory (aka ZafC is a legend):

It all started with some late night viewing of Bradley Phillip's testing of the Akasha. Immediately, my interest was piqued, and I wanted to try one. The Akasha was out of my price point without knowing if it truly was a sound concept. The Axiom is even worse from that stand-point. And being based in Aus, shipping for TJ's T5 SBCAR is more expensive than the actual product (granted, they have now released the STLs for purchase).

Enter ZafC. This incredible creator published their Super BCAR experimental files a few months back. The only downside is until recently it was very hit or miss with the files. The naming scheme wasn't very clear. Now, ZafC has released their Idiom, available in the Super BCAR experimental files. This solved a lot of the "trial and error" testing from before. 

I printed a few test versions (Idiom v1c high crush and medium crush) and was thoroughly impressed. There was only 2 downsides: first, unlike the T5 and Akasha/Axiom which use a collet system (which is objectively better at keeping the SBCAR centered), the Idiom uses o-rings. Second is subjective, but the Idiom does just look like a tube with massive cut-outs. I'm not a fan of it aesthetically. Additional "baffles" and support material does look kind of cool, as well as adding some rigidity to the muzzle device. 

Just when I thought I'd have to recreate it all from scratch, ZafC released the parametric files for their Super BCAR which I have shamelessly based the Umoya off of.

Notes on design

All testing was done out of the following blasters with fresh Worker 1.2g darts at 15m (I am a bit space constrained, hoping to push this out further in another outing):

• MHP Kirrin with a 500mm barrel, 2.0 spring (FPS unknown)

• ZWQ S400 with a 550mm barrel, 2.2 spring (~380FPS)

• Worker Harrier with a 370mm barrel, 1.6x300 spring (~230 FPS)

Unfortunately I didn't have the time or equipment to put together a nice shot grouping image like Atlasunit22 or Bradley Phillips, but I'm hoping that someone in the community will provide.

I've chosen a 10 degree PCAR and 12 degree BCAR section as it seems to give the best results in testing. I increased the porting size in the PCAR section to 4mm with a taper of 1 degree, creating a larger vent. This seemed to work best to eliminate the odd flyer. PCAR crush was chosen to be 12.2mm as anything tighter bleed FPS to an unacceptable degree on anything other than the highest of FPS. The BCAR crush is set to 11.7, and compensates for the loss of engagement on the PCAR to keep the dart stable.

We tested without the support rings in the BCAR section (ala ZafC's original design). However, we did end up dropping a blaster by accident, resulting in the cracking of the BCAR section. This resulted in the 2 support rings added for the final design to give a little more rigidity.

RedCowl's collet system was chosen for its proven reliability, strong lock up, and the fact they've uploaded an open-source dev file. The collar designed for the Umoya has a hole in it to insert an M3 hex key to crack it loose if it gets stuck when assembled. The Umoya itself has a 16.25mm internal diameter for the barrel to sit in, which may be a little tight or loose depending on what barrel you use. It fits and locks onto Worker and ZWQ barrels with no issue, but may need to be edited depending on your barrel tolerances. I've left the grooves for 2 O-16 o-rings if the fit is too loose.

I'm not going to make accuracy claims or comparisons to other options on the market. I'll leave that to the very talented Atlasunit22. However, this has been a huge upgrade to the old SCAR attachments I was previously using.

The files

Included are 3 files:

1. the parametric file with all the cosmetic bits. This is so the community can continue to experiment to see what makes this tick.

2. the STL of the Umoya, with a 10 degree PCAR and 12 degree BCAR.

3. The locking collar.

UPDATE 6 June 2026: There is now just the single beta test STL for the Umoya, using a 12.2mm PCAR crush at 10 degrees, and 11.7mm BCAR crush at 12 degrees. This will be the final beta version before final release once I get testing notes back. The parametric files are still available for download if you're so inclined to mess with it.

Bill of materials and print settings

• 18x M3x10 Countersunk screw

• 18x F683ZZ bearings

• 2x O-16 o-rings (optional)

I would recommend printing at 0.16 layer height for the PCAR section. Otherwise print at normal settings. I have been using 25% gyroid and 4 walls.

The SBCAR will need to be printed muzzle on the build plate, and with tree supports. A small hex key, screwdriver, or pin will be needed to push out the support material from the screw holes.

The supports like to generate under each of the "spacers" for the bearings, so take care when removing the supports and it is worth sanding/filing the contact surface that the bearings will sit on to ensure they sit flat. Installing the bearings is the same as for ZafC's build:

Make sure the flanges face away from the screw head. Don't crank the screw in. Turn until you feel the resistance jump and stop so you don't mash the standoff flat or jam the outer race of the bearing into the print.

The parametric file

Firstly, I apologise that this file is a bit of a mess. I haven't cleaned up a lot of the in-between processes of the file. 

Under the parameters tab, you can find most of the relevant details, including BCAR and PCAR crush, angle, and number of rows. If you've messed around with ZafC's parametric SBCAR file, you'll find many of these settings familiar. 

Conclusion

This all started as a rejection that innovation in this hobby is kept behind paywalls and secrecy. I'm all for creators making money off their designs, but for something truly innovative like the SBCAR concept seems to be, it makes no sense to keep it as a closely guarded secret.

Any resemblance is purely coincidental from adding fillets and strengthening the overall design. Please, download, remix and share your conclusions and setups.

I want to thank again ZafC and all the creators in the Nerf community who open-source their discoveries.

Update notes

20260606: uploaded latest version, reducing the support material as per LSMODS testing. Homologated to be just the 12.2mm crush PCAR.

20260529: hotfix to address issues within the parametric file, as well as provide a medium crush STL version (v1.4)

20260527: Released to public (v1.3)