FPMG Knex Concept Full-auto

About: I used to build K'nex guns. I'd like to think I've grown to be quite good at it, however, I've lost most of my interest in K'nex over my first couple of years in High School, but I do occasionally still come...
hey guys !
this is a concept i thought up while playing with a full auto RBG i made. i'm not gonna be posting the RBG full-auto, cause my friend that built it with me begged me not to (he's kinda greedy and wanted it all to himself). i'm not gonna be posting instructions for this either, but i am going to show you the gun and explain how it works. it's really simple - if you have even a little bit of experience with knex you should be able to build it off the pics and the video.

ROF : about up to 6 per second (depends on the speed you crank the crank)
range : 3-4 feet
comfortability : very comfortable
accuracy : cannot be checked at this point, because the range isn't high enough
mag capacity : 18 (variable)
looks : pretty good
sturdiness/stability : very sturdy/stable
reliability : pretty reliable, jams every 10 mags or so, but can be easily fixed.

anyway, this gun isn't made for performance. as oblivitus has done several times, i have introduced this brand new concept to the knexing community, in hope that people will take it to the next level, because i think, and i believe oblivitus would agree with me, that this gun concept has a lot of potential, and can get up to 30 feet. sadly, this gun does not have a trigger, but there is a crank that you control the gun with. don't leave comments saying "it's lame", "it's weak", "it doesn't have a trigger"... i know all these things. this is only a concept and a prototype with which i tested the concept. i hope this concept will be perfected and, hopefully, get a decent range. if it will, this will be the first firing pin machine gun ever to be built of knex !!! (not including multi barrel and multi ram guns, which, quite frankly don't find any sympathy in me).

i have a great idea how to make it much MUCH stronger. i made only 1 lame attempt at it and quit. what i'm talking about is adding a modification of kinetic's semi automatic mechanism. the one with the pusher that pushes the bullet against a mech that only slightly revolves allowing the bullet to pop out, but since it has a lot of band pressure, it propels the bullets really powerfully. you could add some kind of mod of that in front of the mag and in line with the ram (and bullet, of course), that when the ram goes forward, it pushes the bullet into the mech, which intern, pushes the bullet out of the gun with power. i was thinking of the pusher that pushes the bullets up in the semi-auto gun to be halfway up the barrel, with it's round side facing the bullet, so that when the bullet gets to it, it pushes the pusher (irony) down, and then the pusher pushes the bullet back up into pressure with the firing mechanism of the full-auto.

i sincerely hope i am understood, because this idea is amazing and would make this gun all that much better, cause if you would be able to make a strong, full-auto gun that uses a magazine, and doesn't need any cocking before use and is very simple to use, you would really be getting far.

best of luck to anyone who attempts to perfect this gun, and if anyone does, give me at least 10 percent credit for the idea please.

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    33 Discussions

    Well, I know I am commenting on something that is "kinda outdated" (meaning people don't post comments on this anymore) but I have a thing to ask you. Lets say you put the same mech you have here on a different gun, but instead of the FP being attached to the charging handle / cranking handle, you use your CH to pull back a FP that has a rubber band attached to it, and as as soon as you get to the full extremity of FP, the CH falls below the "grab point" and the FP shoots forward? What do you think, sharir?

    2 replies

    that's a good idea, and many people (myself included) thought about it or something similar before. however, it is very hard to make if not impossible completely. i will not be trying again because i just don't think it's worth a fifth attempt for a gun that wouldn't even be that cool if i were to get it to work. i do encourage you to try though. who knows? maybe you'll be the first to succeed.

    P.S. outdated means the gun/concept itself isn't good anymore, because it has been surpassed by others. a topic no one is commenting on is a dead topic.


    7 years ago on Introduction

    I made a full auto that has the potential of shooting 25+ feet of range, shoots oodammo, the only way I can get it to shoot that good is with a drill. So you should try spinning it with a drill.

    3 replies

    Reply 7 years ago on Introduction

    any video of yours? im not using a drill with knex, that's first. and second, i've taken this down about 30 seconds after making the video. i wasn't gonna keep on working on it, it's just something i made to demonstrate my concept. it's a model, a prototype.


    Reply 7 years ago on Introduction

    I know I was just suggesting something you can use to make it better, and Im going to make a video shortly, when I can get my hands on my dads drill.

    The problem with mechs like this is the pin decelerates as it travels towards the bullet (the crank reaching it's dead-centre), so the force on the bullet isn't great. Overall I like the way it's been built, and I agree it gets insane ROF. The main thing I suggest is to use some sort of leverage system, so the pin accelerates on the forward stroke, instead of constantly decelerating.

    9 replies


    i've thought of that problem, but my idea was not for the pin to actually be the thing firing the bullet, but to be a kind of pusher that pushes the bullet into a mech that flings it away (my idea for the mech was a modded kinetic's semi auto mech). although it will be hard to design one that will perfectly fit and be strong, but i'm just saying, thats the idea. the pin is just pushing the bullets into a firing mech.


    7 years ago on Introduction

    I like the mech but I just had to ROFLOL when I read "Range: 3-4 feet".