Silly Shell Quick Releasing Chuck (QRC) Barrel Attachment

This Silly shell adapter works like a keyless chuck for an impact driver. Pull the collar back and the shell is released. Shells can be inserted when the collar is forward and the catches will automatically snap into place. Zero insertion force is needed to fully seat and seal the shell to the breech face. The adapter can also be left on while firing darts normally because the bore hole has enough clearance for that. Because I like it so much, I've also included an adapter that you can slip the Dart Zone BCAR into. You could also use this EX BCAR shell, or silly's trivictus/merlynn rifled silly shells as PCARs.

Most testing of this has been done on the Aeon Pro X, which is the perfect vehicle for it in my opinion. Mega XL can fire about 60ft, and Mega about 100ft. I've also included parts for standard 16mm barrels and an Out of Darts Little Rocket tri-lug version. So you have no excuse to not be slappin shells on your blaster. If there's a variation you would like, please just let me know the geometry and I will make it for you to test.

It works pretty well overall, except there are two features I would like to add to it: Spring return for the collar, and auto-ejection for the shells. The collar stays locked very well, but not having a spring return means there's just one extra step to reloading. Auto-eject would also reduce the steps needed for reload. You can drop the shells pretty good with gravity, though.

I've included STEP files so if you have a good idea on how to make those features work in this form factor, please be my guest. I've tried levers, springs, ball detents… nothing works well without causing other issues.

(Forgive the print quality in my images. I've been using an old spool of junk silk pla to prototype)

AVAILABLE FLAVORS:

• 16mm OD aluminum barrel clamp
• Dart Zone Pro 19mm muzzle slip-fit attachment
• Out of Darts Little Rocket tri-lug
• 17/32" Brass Barrel (STLs Added 5/29/25)
• Trion Muzzle Lug (STL Added 5/29/25)
• Titan Tank Thread (STL Added 5/29/25)
• SillyMaxx 1400 Barrel (Titan Tank Thread) (STL Added 5/30/25)

PRINTING TIPS:

• Print all adapter bodies with the breech face pointing up, as shown.
• Do your best to reduce your Z-seam to help with clearance for the shell.
• Use grid or rectilinear supports under the body to make support removal easier.
• Elephant's foot on the catches will interfere with the ability to lock the shell. You will either need to trim these flush, print them on a raft, or adjust your printer's settings to avoid this effect. If you have trouble with shells catching, look at these first.

HARDWARE:

• One 20mm OD x 16mm ID x 2mm thick O-ring for the breech
• 60mm of 3mm filament OR Three M3x15 screws OR Three printed pegs
• Two 17mm OD x 14mm ID x 1.5mm thick O-rings for the Dart Zone Pro adapter
• One thin rubber band (1.5mm-3mm thick)

ASSEMBLY:

1. Drill out the holes in the adapter body and the catches to 3.0mm
2. Install the catches with either a 20mm piece of 3mm filament, an M3x15mm screw, or the printed pegs
3. Use a thin rubber band and wrap it around the adapter body so that it lays in the groove and presses on the catches. You may wrap the rubber band twice, but any more will make it difficult to install the collar.
4. To install the collar, start by sliding it on with the chamfered edge first. The catches will be in the way, You can partially insert a silly shell (or shove an MXL shell in backwards) to move these out of the way enough slide the collar on. It may take a little force to push past the rubber band. That's normal. Honestly, once I'm past the catches, I just slap it the rest of the way home and I have had zero issues with the rubber band.
5. Screw on the bottom retainer.
6. Install 20x16x2 o-ring onto the breech face by pressing it into place.
7. If making the Dart Zone Pro adapter: Install two 17x14x1.5 o-rings onto the stem

TROUBLESHOOTING:

• Catches won't lock or will only lock when pressing firmly
  • Not enough clearance on your catch. Remove elephant's foot, if any. You can try a 1.5mm o-ring instead of 2mm. Or you can also gently sand the underside of the catch. Reprint catches with slightly reduced xy contour compensation. Check the thickness of your shell rims. They should be within 0.1mm of 3.0mm.
• Silly shell is loose or rattles around when catches are locked
  • Too much clearance on your catch. Your best bet is to reprint with a slightly increased xy contour compensation. Check the thickness of your shell rims. They should be within 0.1mm of 3.0mm.
• Catches won't stay locked
  • Get a stronger rubber band or double-wrap the one you have
  • This may also be caused by catches not fully locking. See first bullet point.
  • This can also happen when the QRC is located too closely to the plunger head. The shock of the plunger can sometimes shake the catches enough to let go of the shell.

UPDATE 6/23/2025:

I've printed over a dozen of these at this point and have identified a few more potential headaches. Nearly all of them center around the spacing on the catches.

The rims on the bottom of your silly shells needs to be 3.0mm in thickness within +/-0.1mm. I discovered after printing a fresh batch of shells that none of them were locking well. This is because the bed leveling compensation on my printer ended up making the rim too thick. The shells I have that work well are all 3mm on the nose. The shells that don't work are all 3.3mm. If I sand them down to 3.1mm, they work if pressed in. If you find yourself struggling and only some of your shells work, take a look at the thickness of the rim.

Unfortunately, the only fix for this is to tune your catches to work with the thickest rims, which will result in slightly loose holds on the thinner rimmed shells. I will be providing catches with slightly different spacing to make this tuning process easier. Ultimately what this means is if you intend to use the QRC with your silly shells, you will need to make sure you're printing at least the rim consistently. I turned off the Z fade height on my bed leveling, and that seemed to fix the inconsistency between batches.

The other issue I have had is with the rubber band. It's really hard to find consistent rubber bands. One might work great and then the next one is too weak. I seem to have the best luck with 1.8-2mm thick rubber bands that are about 25mm (one inch) in diameter and then wrapping it twice.

I think it best if I address these issues in a V2 of the collet, as it may require some serious rework and engineering time. It works well enough as-is though so I'll keep it available as I do that.

Feel free to incorporate any part of this into a blaster design (with attribution somewhere in the documentation), even if you're selling it. No need to ask. I just want to see foam fly. Non-commercial license only applies to this design directly.

Happy hunting!