Pump Action Knex Concept





Introduction: Pump Action Knex Concept


I have no idea if there are still active knex gun builders on this site, but I first got inspiration for my knex guns on this site, so I though I'd return the favor and share my ideas too. Anyways, this is my latest knex gun. Here are some of its attributes:

- Extremely sturdy construction

- Removable Magazine

- 6.5 inch pullback

- Magazine Release

- Simple and strong mechanisms, nothing fancy

- Moderately sturdy handle

- 50-75 ft range (my best guess, the only two factors lowering the range are the ammo choice (one slot w/white rod) and the friction caused by the pin guide.)

All of these features are relatively standard, but I have not seen a pump action gun as clean looking as this one or with as long a pull distance. I kinda built this gun with the goal of making the best gun possible using tried and true mechanisms, and I think I came close. The pump was added to give it a high rate of fire, and the design was simplified to make it as reliable as possible. The removable mag was a first for me, but in theory that should be very reliable too.

In theory, this gun is everything one could hope for. However, I have not gotten it to shoot reliably due to problems with my magazine not holding the bullets firmly in place.

Also, I want to apologize for simplistic way I try to explain my gun. I'm not trying to be insulting, I just want to be clear.

Step 1: Internal/How It Works

The plunger is placed directly below the barrel to give the pumping mechanism maximum strength, and the pump itself is restrained from all movement besides the linear movement required to reset the firing pin. Also, the pump and plunger are all one connected part, which in my opinion is a big plus because not only is it stronger, but it has less ways to fail.

Step 2: Overview/Conclusion

While this is not my first gun, it is definitely my greatest creation by far. I hope somebody likes the idea and decides to improve upon it. I think the overall design has a lot of potential because 1) it uses only a few broken pieces 2) it is very strong and sturdy and could hold pretty much as many rubber bands as you can pull back (which is quite a lot given the ergonomic pump) and 3) the perfectly smooth pull of this gun along with its full sized body make it very easy to fire rapidly. However, a magazine redesign would be needed to get the gun to shoot reliably.

Thanks for reading! Please comment, I would love the feedback.



    • Science of Cooking

      Science of Cooking
    • Microcontroller Contest

      Microcontroller Contest
    • Spotless Contest

      Spotless Contest

    We have a be nice policy.
    Please be positive and constructive.




    Sorry but I have given up on the rapid fire pump because what I did get it was preaty much the pump pulled the trigger when you pushed it back forward so I could not get it to work by just pulling the trigger. Now I am attempting a pump that works like a real one, you pull the pump and the chamber opens and pushes a bullet from the tubular mag into the chamber. I don't know if this has been done but I have been working on it for a month now

    I dont think it has been done before, but allowing the bullets to be loaded into the tubular mag from one direction, (the bottom), and loaded into the chamber when coming from the front of the gun, and having the pump control when they are loaded is a very challenging mech to make. And then on top of it, you need to get a pump to slide along the "tubular" mag. It would be really cool and impressive if you could accomplish such a feat. Let me know how it goes. Good Luck!

    Yea it will be challenging, I have a pretty good idea of how it's going to work. I don't want to spoil anything but I am tired of having these visions of a gun and telling everyone about it and never successfully get it to work, so I am really going to put my heart in this one. Thanks for your feedback!

    I know the feeling. I myself have started a cool concept where a pump would be used to reload a slingshot style gun. I am currently away at school so the project is on hold but its one of those things that would be really cool but has a high chance of not working out. After all, there is only so much that can be done with knex. But then again, the only reason I build knex guns is for the challenge.

    From what I can tell, this is a well constructed gun-more efficient that other pump actions I've seen

    Well first off let me say it awesome and I LOVE pump action knex guns! I'm glad to see someone else is messing with them as well. I also like that you were able to incorporate a bottom removable magazine. Is it preloadable?

    Yes, the magazine is preloadable. The plunger latches at the bottom of the clip to allow for easy reloading. However the only way I was able to get enough pressure on the bullets I had to add some pieces to the end of the plunger and a longer rubber band. So now the clip has this ugly rod sticking out of the bottom of it.

    Oh okay so its preloadable but you have to secure the mag pusher before loading. I was really curious because your internals are surprisingly similar to my Zip3 model (the major difference being the chambering mechanism). I use the chambering mechanism to allow preloadable magazines because the round is pushed out of the magazine, between the rods that push back the ram rod, and up into the firing chamber.
    Overall good job! I still really like how it turned out. ( I just tend to rant sometimes....)

    I saw your zip3 after I made this gun. I was also surprised at the similarities. I cant wait for you to post it so i can see how you got the mag to line up with the bolt that pushes the bullet into the chamber. Im actually trying to build a gun similar to that. Maybe mine will have 2 barrels if possible, Idk.

    As an aside, I actually sat down several times to take this gun apart and make another, but each time I caught myself admiring it and didnt have the heart to destroy it. I decided i better have a really good idea to replace this gun.

    Yeah that's kinda how I feel about Zip3. I like it a lot, and I can't really see something replacing it but that's why I make instructions....and the next Zip in the series. =P