"Gunzo the Great" Knex Semi-Automatic Rubber Band Gun




Introduction: "Gunzo the Great" Knex Semi-Automatic Rubber Band Gun

This is a Semi-Automatic Rubber Band Gun (by which I mean it SHOOTS rubber bands, since I think the ones that shoot rods hurt too much). It's designed to be as RUGGED as possible, because I was tired of stopping our RBG wars every 2 minutes because somebody's gun broke.

The spacing of the 2 gears that make up the repeater mechanism at the heart of this gun was adapted from MrRadicalEd's RBG Repeater, because it's so simple and works better than all the more complicated ones I've made or tried.

Picture 1: Complete "Gunzo The Great"
Pictures 2&3: Shows my adaptation of MrRadicalEd's 2 gears. (just a model demonstrating the size and relative positioning of the gears)

Thanks to MASTERMIND for the piece count:
6 white connectors (8-way)
38 yellow connectors (5-way)
6 green connectors (4-way)
20 red connectors (3-way)
4 light gray connectors (2-way)
2 dark gray connectors (1-way)
2 blue tabless (or tan tabbed) clip connectors

97 green rods
34 white rods
9 blue rods

7 blue spacers

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Step 1: The Gun Sides

Build 2 of these. These are the Gun Sides.
Note, the Red Connector in the middle is missing in a few of the later pictures. That was a mistake. It is always supposed to be there.

Step 2: Trigger and Spinner Wheel

Picture 1: trigger pieces. Note the blue spacer, and the dark green rubber band.
Picture 2: spinner wheel

Step 3: Barrel Pieces

Make these Barrel Pieces and set them aside

Step 4: Handle Pieces & Odd Parts

Pic 1: Make 4 of these. We'll call these "Handle tips"
Pic 2: Make 2 of these. We'll call these "Handle Spacers"
Pic 3: Make 1 of each of these. They are the "Red Handle Base" and the "Yellow Handle Base"
Pic 4: These are called "Through Rods" or Thru-rods. (All Orange connectors are temporary)
Pic 5: These are Side Clips. You'll actually need to take the grey connector off of the white Snowflake connectors, and replace them at the end of step 9.

Step 5: Assembly: Trigger Area

Pic 1: Slide Thru-Rods through the back side of one of the Gun Sides
Pic 2: Turn it back over
Pic 3: Hold Trigger pieces as shown
Pic 4: Place Trigger on Front Thru-Rod, and a blue spacer on Rear Thru-Rod
Pic 5: Add Spinner Wheel. then another Blue Spacer to rear Thru-Rod
Pic 6: Add Orange connectors to both Thru-Rods. These are just temporary.

Step 6: Assembly: Handle

Pic 1: Add Yellow Handle Base
Pic 2: Add Red Handle Base
Pic 3: Add a handle tip as shown
Pic 4: Add all handle tips
Pic 5: Add handle spacers (gun has been rotated, but not flipped)
Pic 6: Add second handle spacer (the gaps are not necessary)

Step 7: Assembly: Barrel Top

Pic 1: Attach these barrel pieces
Pic 2: Attach yellow connectors as shown (I used grey ones so you could see the layers better)
Pic 3: Attach 2nd yellow/grey
Pic 4: After attaching 3rd one, you can add the green rods
Pic 5: Repeat steps from Pics 2-4, to create the second internal layer

Step 8: Assembly: Barrel Bottom

Pic 1: Add one of the remaining Barrel pieces as shown, adding one more green rod .
Pic 2: Add 1 green rod to the bottom of each of the 6 center yellow/grey connectors)
Pic 3: Attach a yellow connector to the blue rod. See pic note.
Pic 4: Then slide the yellow down to snap into layer 2. Add the green rod.
Pic 5: Make 2 pieces like the one shown here. The other is shown already attached. Do it now.
Pic 6: Repeat steps from Pic 4-5 to finish layer 3
Pic 7: Add final barrel piece, then insert green rod where pointer is pointing

Step 9: Assembly: Finishing Up

Pic 1: Compress all pieces on blue rods. remove orange connectors from thru-rods
Pic 2: Add second gun side, sliding over thru-rods, snap into place.
Pic 3: Add blue connector to rear thru-rod. Add orange connector to front thru-rod
Pic 4: Snap in blue rod, with 4 blue spacers
Pic 5: Remove orange connector from front Thru-Rod, replace with white "snowflake" connector. repeat on both sides, making sure they're oriented the same way.
Pic 6: Rotate the snowflake clockwise until the blue rod is in the SouthWest corner, and the other blue rod is straight below the center. It will be tricky to work it past the other blue without disconecting either. Attach green rod and grey connector as shown. Repeat on both sides.
Pic 7: Attach Side Clips as shown, on both sides.
Pic 8: Arrange trigger spacer and rubber band as shown, the spacer will keep the RB from getting chewed up as you fire the gun.
Pic 9: stretch rubber band over tip of gun and seat as shown
Pic 10: Insert white rod through base of trigger.
Pic 11-12: Use a rubber band to secure the white rod in place. Pattern doesn't matter, it just needs enough tension to not slide out.

Step 10: Loading Rubber Bands & Trouble-shooting

Sorry these pictures are so dark. I'll try to take new ones in daylight.

Pic 1: clip Rubber band in gun tip. Stretch to the spinner wheel.
Pic 2: Insert the rubber band behind the first white rod that is pointing backward.
Pic 3: NOTE: make sure you get the RB in the V of the connector,
Pic 4: WRONG WAY: If you do it like this, the rubber band may get stuck, and misfire.
Cock the gun by pulling the wheel backward until it clicks once.
Start again at step 1. Always put the RB on the rod in the position shown in Pic 2.
When you go to fire the gun, the first time you pull the trigger, it won't shoot. Rubber bands begin to release on the second pull.

PROBLEMS: If you pull the trigger once, and all rubber bands fly off, you may have put on too many Rubber bands. It all depends on the type of RBs you're using, and the stiffness of your Knex pieces. Try this. Load only 2 RBs. Fire the gun. If the rubber bands shoot individually, as intended, reload the gun with 3 RBs and see if that works. Keep working up until you know the limit of your gun. If the gun still misfires with only 2 Rubber Bands, make sure all the connectors are snapped, especially inside the trigger chamber. If that still doesn't help, try bigger RBs or shorten the barrel of the gun.

Step 11: Variations

Here are some pictures of a wider variation of the semi-auto assembly. Note, the major difference is 2 blue spacers on either side of the revolver spool, instead of 1. The down side is, it requires Yellow Through rods, which is a little annoying on a pistol, but is no problem in a Rifle.

Pic 1 - Overview of the Original Build of the Semi-Auto Assembly on the pistol. Here you REALLY see the similarities to Mr Radical Ed's.

Pic 2 - Overhead view of pic 1

Pic 3 - My sniper variant - Shoots 12" bands I got at Staples / Office Depot

Pic 4 - Sniper Semi-Auto Assembly

Pic 5 - Barrel Detail for the Sniper Rifle

1 Person Made This Project!


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90 Discussions


Reply 6 years ago on Introduction

there is better (not that this isn't good) likes the s3. its is semi auto and shoots pieces.

Inventor X
Inventor X

8 years ago on Introduction

This is totally my choice of weaponry in a RB war. Compact, sleek, and has a ncie look. The trigger is a light pull, and has modding capabilities. Thanks for building such a great gun! (No wonder it's called "Gunzo the Great" !) :)


9 years ago on Introduction

I LOVE this gun. It's a big gun, which is sweet and all, but for people with only a few pieces, (like me),well, it uses a lot of pieces. It is WELL worth it, though. =D 5*, you deserve it.


10 years ago on Step 1

danroy, its clear enough to "see" and make
so why complain?


Reply 10 years ago on Introduction

Yep, that's the same one I mentioned in the description. Thanks to Mr. Radical Ed's design. I think I'm going to send him another thank you note.


10 years ago on Introduction

Hey, this is really great design. You managed to make the gun strong without requiring us to clip 7 connectors onto a rod all at the same time in an internal space while doing a dance and baking a pie.


Reply 10 years ago on Introduction

Yeah, thanks. I'm not a big pie fan, and I'm a terrible dancer, so I never got into that style of Knex Design.


10 years ago on Step 1

you can still see what your doing


10 years ago on Introduction

rev nice gun but i need a bit clearer instructions sorry but adleast this gun is still the best rbg pistol


Reply 10 years ago on Introduction

Thanks for that encouragement! I know the gun can work well, although it apparently doesn't work for everybody. I thought maybe my instructions weren't clear enough. I'm glad you were able to use them for a successful build.