K'nex Blow-back Pistol



Introduction: K'nex Blow-back Pistol

About: I do K'nex...a lot. It's fun to mess around with new mechanisms, and to learn about basic engineering. I build mostly guns, and love to build new concepts. I will start posting some of my 'unposted ideas' in...

Yep...you probably read the title, and thought this would be a pistol with a slide on top that moved like a real gun. Sorry, but that's not what this is, and, frankly, I don't think I should post this, just because I don't like it. But, I decided to, just in case someone wants to build it or look at it. So, here we go.

This IS a blow-back gun, just not the usual type of blow-back. Like on an M4 or an AK-47, this has a charging handle that acts as the blow-back. Unfortunately, this gun shoots rubber-bands, and at that point, they don't go very far, (I'm working on it). Also, this blow-back is NOT reversed, it just uses and 'open-bolt mechanism', which is used on guns like Uzi's, Mac 11's, and other sub-machine pistols. This 'open-bolt mechanism' features the bolt going forward on the shot, instead of back.

This pistol looks hideous, I know, but i don't know what to do. Technically, the top bar of the gun isn't necessary, so you could make the whole top row Yellow Connectors, but otherwise, there isn't much you could change about this gun. So, here are some Pro's and Con's, (I'm very disappointed that I couldn't get this gun to be better, but oh well).



Blow-back! Yay!

Fun to play with


Not Comfortable...at all

Horrible range, 10 feet at best for me

Frequently jams if your rubber-bands aren't strong enough

Looks absolutely hideous

Semi-Auto doesn't work very well, also frequently jams


For these reasons, I'm not going to post internals unless someone wants them, because I'm not very proud of this gun, and could care less if someone built it or not, (I'm kinda being a bit harsh :/).


Here's a link to a video, (watch until the end to see it work).



But yeah, hope you take a look at it, and maybe improve it! By the way, if you want to mod this gun, start with the trigger, that's the biggest problem. Please leave your thoughts in the comment section!



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    11 Discussions

    Did my comment not appear? I hate it when Instructables is just like, no, you can't post the comment that took you 10 minutes to make. Oh well, I suppose I'll make another one tomorrow. If I make one tonight it probably won't make much sense as I am half asleep right now.

    Okay, sounds good....you might be on what I was on a little while ago. The thing is, instructables thinks your comments have been harsh lately, (which for you I'm sure they aren't), so all your comments have to go through the instructables people, which takes days.

    Wow..... so much negativity here..... lol. Seriously chill people! Anyway.... about the gun. Like all your others I'm very interested in it. I especially like guns like these that make semi auto seem closer. I don't know exactly how this gun functions but I'll be looking for updates!

    1 reply

    I want him to chill too haha....but thanks for the comment, and I'm soooo close to finishing my full-auto gun. I could reach out and touch it if I didn't have one problem. I'll probably make this look better eventually, and will be posting internals tomorrow.

    Hey hey hey, trust me when I say I didn't rip the trigger off your gun. I didn't say this, but I based it off of myOmy's new fully automatic gun thingy, but that trigger didn't work out the best, so I modded it to a point where it really wasn't his anymore. If this somehow made it your trigger, sorry, I didn't know. And, no offense, don't say if it wasn't for you, this gun wouldn't have existed, because you're not the only person out there who can build stuff. And you better trust me when I say, if I copied your trigger, I would have said so, and actually asked permission first.

    And don't stop posting your stuff. You're a great builder, and keeping your stuff hidden is a disappointment to some people.

    Not to down-grade you, but in real life, this actually is called an open bolt blow-back system...but thanks for the feedback, and once I post internals, I think you'll find it's a bit different from your beta bmbbr

    I would like internals, also try uploading to YouTube cos your video sucks it's all most unwatchable!

    1 reply

    Sure I guess I'll put up internals, but I have nothing else to take videos with. It's not that it's not YouTube, it's because of my laptop camera. It's very laggy, and My phone can only take 30 second long videos with very poor quality. So, sorry that it sucks, but that's the best I have.