Caliburn Mag-Fed Pump-Action Nerf Blaster

by captainslug, published

Caliburn Mag-Fed Pump-Action Nerf Blaster by captainslug Jun 11, 2017
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CHANGE NOTE 3/17/18: Many small changes. Most of them deal with print quality and reducing time needed to finish or deburr parts during assembly. Spring peg of SEAR5 updated to match the one of the MagRelease so that the spring is more captive. Magwell and Grip both now include through-holes for their short pins through both sides of the part so that disassembly or extraction of the short pin is possible. Muzzle piece now uses 4-40 lock nuts and 4-40 screws to act as set screws for retaining the barrel.



r1: http://captainslug.com/nerf/Caliburn3DPAssembly.pdf
r2.0: http://captainslug.com/nerf/Caliburn3DPAssembly2.pdf
r2.2: http://captainslug.com/nerf/Caliburn3DPAssembly3.pdf
r2.6: http://captainslug.com/nerf/Caliburn3DPAssembly4.pdf

Blaster is compatible with FULL-LENGTH and Half-length dart magazines. It is also capable of loading 1 to 4 darts at a time by simply cycling the breech more than once per priming stroke.

The Caliburn is a Mag-Fed Pump-Action Homemade Nerf Blaster design released as a PUBLIC DOMAIN file set by Captain Slug (http://www.captainslug.com).

WARNING: This blaster MAY NOT BE SAFE FOR INDOOR PLAY. Even with the weaker spring, the o-ring removed, and firing full-length darts this blaster will easily shoot faster than 150+ fps. So keep this in mind as to where and when this blaster is used. It can and will produce welts at point-blank range.

You are welcome to and encouraged to modify the files in any way you want. The Majority of the parts can be printed with infill as low as 20% in PLA, but I would recommend printing in layers of 200 Micron or smaller.

The Following parts however ARE REQUIRED to be printed at 100% infill: Sear, Spreader, and Ram2o.

This Blaster design is also offered in a version you can machine out of polycarbonate if you are interested in crafting one from scratch. The write-up and machining templates for that version are available at: http://captainslug.com/caliburn.html

Assembled Blasters and Blaster Kits are available for sale as commissioned items.

Hardware kits to allow you to assemble on you've printed yourself are restocked nearly every weekend.

All of the above are for sale on Etsy as well as eBay.




Print Settings

Printer Brand:








300 micron


100% for some, 25% for most


None of the parts will require support material.

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I have an aluminum ramrod and the PLA base piece ("back half"?) is starting to deform a little, so I'd like to print my own replacement. However, I can't seem to find just the back half on its own within the Caliburn STL files -- I can see RAM2O.stl and Ram2on.stl, but those include the ramrod as well rather than just the back half.

Could you make the model files available for the back half?

Is everything that needs to be made in a lathe included in the hardware kit?

The kit includes every piece of hardware cut to length and ready for assembly. It does not include a ramrod so you either have to purchase one of those to go with it, or print your own.

where are the parts that are supposed to be printed in 100% infill they are missing in the newest zip file

Is the folder labeled 122717b the most recent set of parts that I should be printing? I've already printed all of the parts from here but I've noticed that these parts seem to be different from most of the ones I'm seeing in videos.

They are the most recent. You can assemble them from the version 4 instructions. Most of the videos online are about the r1 version.

What is the Ryan Tube and where is it used on the build? Thank You Master Slug!

You slide it onto the front end of the plunger tube.

Cannot download latest compressed zip file.

I just downloaded the files and It seems that the folder 'Caliburn_3DP_122617' comes back with a 'Compressed Folder Invalid' error. Is this happening for anyone else?

Is the Dart Jam a replacement for another part? A replacement for Jam 2 ?
Thank you Captain Slug!!

It combines the dart guide and jam parts.

Is the spreader no longer needed. I looked at the latest instructions and it shows it being used. I have been looking for it in the files.
Either way I am about half way printing one of you awesome blasters in purple and red and was just looking over the parts list and noticed my question.

Yes it is used. It's in the 100percent folder with the sear.

What design software do you use?

Alibre Design 12.1. It's old, pretty crappy, and crashes a fair amount in Windows 7. Also won't work in any version of Windows newer than that. I'm stuck with it for now because it's what we use primarily at work.

If you want software that's usable go with Fusion 360. I haven't had time to learn it beyond using it to share assemblies with friends.

How big is the largest part that needs to be printed?

The largest parts are the MAG WELL (127.6 x 108.7 x 44.4 mm) and FOREGRIP (107.2 x 81 x 47.6 mm). I am able to print everything on my 152 x 152 x 158mm build area, but it takes roughly 25 hours to print everything. The RAIL_TOP is the longest piece, but will fit diagonally as provided in the STL file.

If you have a build area smaller than I do let me know if you need help getting certain parts that won't fit on your build plate.

Thanks Capt. The Monoprice Mini v2 is a popular printer, and has a print area of 120x120x120. With my calculations, the Magwell just barely can't fit. If it's possible to make it ~124mm or ~125mm instead of 127.6mm, I'd think it'd fit for those of us with tiny beds.

Also, is there a direct link to the HW-only package? Would like to buy the metal parts and springs from you, but have the fun of printing this myself.


There is a 120mm build area Remix available.
I just recently tested it myself and it works, though the assembly process is a little bit different than the standard file set. I include enough extra 4-40 screws in the hardware kit that you can print that version and attach Grip5a to the back of Magwell4a. When joining the front assembly and the rear assembly you also have to make sure to guide the Trigger into the rear half of the grip or it can hinge down and get in the way.

Nerf Caliburn - 120mm Buildplate Magwell and Grip

How'd I miss this? AWESOME!

Thanks. The printer I am looking at getting (my first one) only has a 120 mm square build area. If I do get the printer then it won't be for another month.

Can you post a list of the parts in the hardware kit so I could buy them myself when they are out of stock?

You will find that under the first "Spoiler" button on the first post of the Nerfhaven Thread.


You will end up paying $100 + shipping and will have to cut everything to length yourself. Here's a cut list you cross-check against the Hardware Kit list and the CAD Files.

Threaded rods: 14, 14, 13, 13, 13, 13, and 8 inches
Aluminum tube spacers: 11.25, 11.25, 11.25, and 6 inches
Plunger Tube: 7.375 inches
1-1/4 SCH40 Pipe for stock: 3 inches
5/8" Delrin Rod: 3.5 inches
.527" ID Barrel: 14 inches

Here is the drawing for the Bolt Arm pair.


I am selling the skirt seals through ebay for a lower shipped price than McMaster.

Hey captainslug when I downloaded the files it only includes the files for the plunger tube parts can you please help me thanks