UKP .31 Caliber (Universal Knex Pistol)




About: I've been building and engineering since as far back as I can remember. My first building toys were those wooden blocks, and at age 4, I upgraded to cereal box samples of K'nex. I also participate in sports,...

Here it is... what some of you might have been waiting for. 

Key Features:
-Under barrel laser (non functioning)
-Trigger guard
-5 round removable mag
-3 round removable quick clip with a reload time around 1.5 seconds, you read right, 1.5 seconds
-Iron sights
-Yes, it is a slightly different handle system than the TDS... don't say its the same, please.

-Small mag
-Accuracy is fairly low after 20 feet

-Amazing look (in my opinion)
-20-40 foot range depending on bands, not bad for a pistol
-Fast fire rate, you can fire the 5 round mag in about 6 seconds 
-Compact size 
*All of these factors make this pistol a superb choice for a secondary in any Knex war*

I know someone somewhere is saying "but my oodammo pistol has the same fire rate and a 13 round mag and better range" 

To that I say, "Then use it, but if you ever decide to look for a more tactical, realistic weapon to use as a secondary in a Knex war, then I suggest you come here first." 

I know my weapon will not compete with an oodammo pistol... so don't say that... what I was going for with this a tactical weapon with good looks that could be used in a Knex war, and thats what I achieved.

Without further ado, I present: The UKP .31 cal (yes I did the math right this time... don't look at the forum topic... just don't... it's fail math conversions)


Step 1: The Main Body

This is the main body of the gun... hence the title... 

Follow the yellow boxes, they will provide you with useless information at most times, but that one time you need help, the yellow boxes will help.

*READ the box on pic 5... If the gun doesn't feed right because you didn't read it, don't complain...*

Step 2: The Handle

The barrel and handle are sort of merged together.. not 2 separate parts... so the build just continues building off the barrel... you'll see when you do it...

Please note the boxes If your a lefty, I built the gun being a righty... so the handle is formed for a righty. the boxes will tell you how to correct it for a lefty.

Step 3: Trigger

Easy enough...

Step 4: Fake Barrel


Step 5: Fake Laser and Real Trigger Guard

Well probably the most painful part of the build... and yes I forgot another picture... to finish the connection of the trigger guard just take the red 3 ways and slide them on the blue rod, really the only place it could go...

Step 6: Side Plates

Just to make the gun look better... build em' unless your way low on parts

Step 7: The Mag and Firing Pin

Last thing to build 

Step 8: Loading and Firing

I'll have a video of this and other stuff... but for now... 

The ammo is pictured below, and look its happy to see you! 

Take 3 rounds for a quick clip or 5 for a standard clip, pictures of each below

To load a standard mag, insert the magazine with the green rod prongs pointed towards the back of the handle and push up until it doesn't go any farther... It locks in place internally, you'll here a click when the mag is all the way in... next get a ram rod and shove it through the bottom of the mag and attach a rubber band.... then pull the ram back and shoot.

To load a quick clip (my favorite, fastest reload) pre assemble the quick clip assembly... insert the mag the same way as a 5 round mag... then pull the blue pin and the gun is then loaded and ready to fire! around 1.5 seconds 



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    46 Discussions


    Reply 7 years ago on Introduction

    v3 is in the works. I played with v2 too much and got the slide messed up when I was trying to make it longer. V3 will outclass the both of these. hopefully


    6 years ago on Step 8

    hey man, i really like this, i think im going to build it but dont the bullets fall out of the mag easily?

    2 replies

    Reply 6 years ago on Introduction

    not really... just stick a piece of tape over them when transporting. then pull it off before you load.


    Reply 6 years ago on Introduction

    USP- Universal Service Pistol. UKP- Universal Knex pistol. Just goes with the name.


    6 years ago on Introduction

    Best. Knex. Gun. EVAR!!!! 5 stars to you bro :) But how does the mag work. When I put the ammo in and then the mag rod, they fly everywhere! Plz help :(

    2 replies

    8 years ago on Introduction

    Just throwing this out there... has anyone built this yet? if so what needs to be fixed? or clarified in the instructions? I know if there are build problems the gun WILL jam so... yea... post anything that goes wrong and I'll get on fixing it!