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 12/11/17: Small changes to tolerances on Ram2o so that even prints that have flash on the underside edge of the print will still fit nicely in the plunger tube.



r1: http://captainslug.com/nerf/Caliburn3DPAssembly.pdf
r2.0: http://captainslug.com/nerf/Caliburn3DPAssembly2.pdf
r2.2: http://captainslug.com/nerf/Caliburn3DPAssembly3.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: Bolt1, P1, P2, P3b, Ram2, Sear, and Spreader.

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. P3b turns out ugly on some printers but will work with a little light sanding on its exterior. Some users have seen bed-warping in the sides of the Grip assembly, I'm not sure that it would really impact assembly much.

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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 50 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. 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