Introduction: Barackuda

About: Just an aging K'nex launcher builder

It's been years since I've shown the first version of what would be the Barackuda and now I've finally gotten proper instructions. Long story short, it's a bolt action launcher with a compact drum magazine. While I had hoped to turn it into a competent war launcher with enough work, it never performed quite as well as I was hoping, so instead the novelty is purely in how compact it is.

Just a reminder, I've setup a blog here where I post most of my activity other than instructions. Anyway, let's move onto the instructions.

Parts list:


  • Dark grey/purple one-slot: 87
  • Light grey/light orange two-slot: 21
  • Orange/brown two-slot: 34
  • Red/granite three-slot: 41
  • Green four-slot: 8
  • Yellow/grey 5-slot: 76
  • Blue 7-slot: 2
  • White/black 8-slot: 3


  • Black/clear: 3
  • Tan: 2 (Ideally, all red rods should be tan if you have enough)
  • Red: 11
  • Blue: 10
  • Silver/white: 72
  • Green/black: 157


  • Sockets: 2
  • Ball joints: 2
  • Dome halves: 2
  • Chain connector: 1
  • Blue caps: 6
  • Tan locks: 15
  • Silver spacers: 9
  • Blue spacers: 28
  • Black Ys: 48


  • #64s: 2+
  • Smaller bands (e.g. from newspapers): 3

Step 1: Main Body - First + Second Layer

The Barackuda was designed to be compact, so the main body is based on the Oodassault 3's design, giving it just enough durability for an otherwise slim barrel. This is one of my more complicated designs, so I got a plethora of pictures, hopefully allowing anyone to build it without much fuss.

Step 2: Main Body - Inner Layer

Here we start the barrel and the feed ramp. This should all be pretty easy.

Step 3: Main Body - 4th Layer + Trigger

I had to figure out something unconventional to allow a sear to fit in this tiny pack that still maximized striker length as much as it could.

Step 4: Main Body - Other Internals + Handle

Here we finish up the feed ramp, magazine catch, and start the handle

Step 5: Main Body - Outside Layer + Rear Sight

Here we finish up the outside of the main body and add the rear sight. The rear sight block will hold the front of the striker guide.

Step 6: Handle Details

And here is how we finish up the handle. I tried to make it a little more comfortable than most handles but the nature of K'nex and their blockiness limits the ergonomics a little. To aid in the compactness and structural stability, it's a thumbhole handle-stock design.

Step 7: Stock - 1st and 2nd Layers + Some Internals

The stock is, I'll be honest, a little rough given the design of the main body. It's not attached conventionally. The stock is designed to be rail for the bolt to travel within to facilitate quicker charging of the launcher.

By this point, you can get a little creative with how you want the stock to look if you're experienced. Just be careful with the parts connecting it to the launcher.

Step 8: Stock - Middle Layer + Striker Guide

This launcher didn't use to have a striker guide, but it was one of the improvements I knew I should make. Due to the unconventional stock attachment, I had to make an equally unconventional striker guide attachment point. It's attached pretty securely to the stock.

Step 9: Stock - 4th and 5th Layer

And now we'll finish up the outside of the stock. Again, if you're feeling creative, you can adjust the design however you want as long as you end up keeping the main attachment points.

Step 10: Connecting Stock to Launcher

Short but important step. Again, the stock connection method is very unconventional. A lot of the weight is being directed into the bottom of the handle. I try to prevent some side-to-side wobble by connecting the stock at the top on the outside as well. Still, it won't be the sturdiest stock connection, so I don't recommend handling the weapon via the stock.

Step 11: Bolt Handle

Ideally, if you have extra tan rods available, use those instead of red rods for extra strength.

Step 12: Finishing Trigger and Adding Bolt Pin + Handle

More quirkiness in design due to compactness. The trigger slides up against the bolt pin and keeps it in position. The bolt handle connects loosely to the bolt pin.

Step 13: Striker, Striker Guide, and Bands

Here we finish setting up the launcher to fire. Unfortunately the way the bands are setup makes them difficult to replace. Getting them through the spacers can be tricky, but you'll get used to it in time.

Step 14: Magazine Internals

Here is the magic of the drum magazine. The dome pieces are important for keeping the rods at just the right distance to help them feed reliably. The ball joints are also important for being just the right height to push them reliably.

Step 15: Magazine Shell

Sorry if this is a little confusing. Basically you repeat the same steps 6 times to complete the majority of the magazine shell. Again, ideally, if you have them available use tan rods in place of red rods. I only had two so I figured the best place to use them was the top of the magazine.

Step 16: Finishing Up Magazine

These are the last bits to make the magazine work.

Step 17: Loading and Operating

This is complicated enough I decided to just make a video for it. Follow along for proper handling and operation of the launcher. Don't do anything reckless and have fun! Let me know what you think and post pictures of your own modified versions.