Introduction: The K-2: K'nex Slamfire Rifle

Picture of The K-2: K'nex Slamfire Rifle
Introducing the second in my line of new and innovative guns: the K-2 slamfire full-auto burst.

The K-2 is a pump action rifle, but unlike nearly every other gun out there, it has no trigger.  As the pump (its a handle pump) is pushed, the gun fires fully automatically, up to 4 shots.  It has an eight-shot turret, but would be compatible with a tr18 turret, allowing for more shots and more rapid fire.  

The key to this gun is in the pump, which only engages when it is being pushed and disengages when being pulled back.  This allows it to trigger the hammer as it is moving forward, and then simply slide past it when you are resetting it.

Problems and fixes:
8-shot turret: I only have the pieces for an 8 shot turret, which puts this rifle at a disadvantage because it goes through shots so fast and because an 8 shot turret has a big gap between shots, allowing for the hammer to misfire if the turret doesn't get its shot in place before the hammer is set off.  Simply adding a tr18 turret would solve all these problems.

Power:  Because the hammer is not as strong as it should be, it breaks if any more than two number 64 rubber bands are put on it.  Although making a stronger hammer would be simple, it may require some remodeling of the rest of the gun to accommodate it.

Other potential mechanisms:  The pump was originally designed to rotate a cog, however the spacing between the teeth did not match any possible diameters for a cog that I could come up with.  This is why the gun has to have handle pump rather than classic pump.  However I have come up with two different mechanisms that will fit between the pump and the gear, making the spacing of the teeth in the pump irrelevant.  This will allow for many new possibilities, including a trigger-fire full auto that can be "recharged" simply by pumping the gun.  

Hope you guys like it, I've been working nonstop for the past 4 days on it, so better like it!



Hunting Rapt3r (author)2012-02-09

no sights i guess:/

H1T4TCH1 (author)2012-02-05

Wow, Kinetic, you're always surprising me!

PotatoCoffee (author)2012-01-14

Nice great pump!

Kinetic (author)PotatoCoffee2012-01-15

Thanks! I hope that I apply it to other mechanisms; that would be great.

PotatoCoffee (author)Kinetic2012-01-28

Profile picture, I went to da Da Vinci Expiditon in London.

oodalumps (author)2012-01-16

Make it smaller. A lot smaller.

Kinetic (author)oodalumps2012-01-16


oodalumps (author)Kinetic2012-01-16

Like this.

superbestknex (author)oodalumps2012-01-16

you mean no stock

oodalumps (author)superbestknex2012-01-16

I mean make it so that the turret doesn't move with the pump. The way he has it set up just makes it huge.

Kinetic (author)oodalumps2012-01-20

The problem with that is that there would need to be a mechanism between the hammer and the pump to reverse directions, and that would just be more weight for the hammer to overcome. If I can get a cog working on this I might be able to get it to work that way.

oodalumps (author)Kinetic2012-01-20

Could make it so that you just pull it outwards. It would probably be better in stabilizing the gun, too.

superbestknex (author)oodalumps2012-01-19

oh thank you for explaining

DJ Radio (author)2012-01-18

WHOA, that is one ridiculously good gun. I thought I knew your limits but I was wrong. I just wish it was a bit smaller. 5/5.

Kinetic (author)DJ Radio2012-01-20

Yeah, size is something I have to work on, but I am finally getting decent power out of the v.2

Find out how many different ways you can put a thousand pieces together and you will know my limits.

Football viking boy (author)2012-01-16

really good job, keep up the work! 4.5* can't wait to see it posted eventually

I will should check out the v.2

tytiger33 (author)2012-01-16

You going to be posting both new guns?

Kinetic (author)tytiger332012-01-16

I will be posting this one as a V.1, but not the K-1. I have some work to do on the hammer to increase efficiency, so once I get that figured out I will post it as the V.2

tytiger33 (author)Kinetic2012-01-17

Ah thank you. I appreciate all the work you do for the Knex community.

Kinetic (author)tytiger332012-01-20

Thanks man, really happy you see it that way.

Kinetic (author)2012-01-16

Ok, so I did some measurements, and the gun gets about 35 feet max. I can post it as is, which will take a couple days, and then work on a V.2. OR I can get started on a V.2 right away, which will likely get around 40-50 feet (maybe even more). Which would you guys prefer?

mulletman6 (author)Kinetic2012-01-17

Do instructions for this one - give us guys something to play with while waiting for V.2 :P

jollex (author)2012-01-16

Great job man, you are really making some great advancements in innovation with your guns, keep it up.

Kinetic (author)jollex2012-01-16

Thanks! You been working on anything lately?

jollex (author)Kinetic2012-01-16

No, I actually haven't worked on anything in a while, but I may be getting back into it if I have time.

mahmel (author)2012-01-16

I cannot see in the video if it's hard to pull the pump, so is it hard to pull the pump?
Ohyeah awesome idea but I think you know that already haha

Kinetic (author)mahmel2012-01-16

The pump is pretty easy to pull, even with the four #64's I have on it right now, and with the v.2, should be even easier with the increased efficiency. And yeah, I'm a fan of the idea too xD

mahmel (author)Kinetic2012-01-16

Ghaha. Nice.

Oblivitus (author)2012-01-14

That's awesome. So it appears to be quite easy to pull the pump right now and I'm assuming that if you made a stronger hammer and put more elastics on it, it wouldn't be unreasonably difficult to pull the pump? That would be great. Brilliant design.

Kinetic (author)Oblivitus2012-01-15

Thanks. I've been working on it since I posted this and I was able to get rid of a minor design flaw that caused the gun to catch onto the rubber bands, greatly reducing efficiency and causing the hammer to break. Now the hammer can withstand the tension of three #64's, and with a little bit of super glue, upwards of four. At the moment I am getting around 35-40 ft.

More importantly, if you read the other potential mechanisms, I think we could use this kind of pump to wind a spool to power your SA, eliminating the need for "power packs". I took a quick glance at you and Sharir's work and it is really impressive. I didn't spend too much time trying to figure it out but I think I understand the different mechanisms and their purposes. I think this mech would be a great addition to your gun once you've gotten it working.

Oblivitus (author)Kinetic2012-01-16

That range is awesome. I can't wait to see a video.

Yes, a pump like this would certainly be an excellent way to increase the cocking rate on the 3252. Good idea. That would be a huge improvement if you or we could design one for it.

~KnexBuild~ (author)2012-01-13

Awesome! That would be really cool if you had a TR-18 turret on it.

Kinetic (author)~KnexBuild~2012-01-15

Yeah, I have upped the range to about 40 ft and as soon as I get a tr18 turret I'm going to post it.

~KnexBuild~ (author)Kinetic2012-01-16


beanieostrich (author)2012-01-13

This is great man. =) I definitely say keep working on it. But i'm not entirely sure how the slamfire works. The power seems a little low though but I understand, its only a concept gun. And I agree, it should probably have a TR-18 turret if it went through 4 rounds in 1 second. Great work Kinetic as always!

Kinetic (author)beanieostrich2012-01-15

The idea is actually very simple. Each tooth pulls back the hammer until it slips, and with 4 teeth in a row, this process happens 4 times for each time the pump is pushed. I have dramatically increased the range over what you saw in the video, and as soon as I get a tr18 turret on it, I am going to post it.

beanieostrich (author)Kinetic2012-01-15

Thanks for explaining it. And im sure quite a few people will build it if you post. =)

mulletman6 (author)2012-01-14

That's pretty damn kool - are you going to post this one?

Kinetic (author)mulletman62012-01-15

Yes, this one will be posted. I have maxed out the range to around 40 ft (with a little super glue xD, about 30ft without it) so I think its pretty postworthy.

mulletman6 (author)Kinetic2012-01-15

Awesome dude. I've got a 18 shot turret already made, so will put that on and see how it is :)

ryry2011 (author)2012-01-14

Dude you build the coolest things ever.

Kinetic (author)ryry20112012-01-15

Thanks man. Speaking of that I havent seen any new guns out of you in a while, you were one of the most active builders on here :(

Anything new you're working on?

ryry2011 (author)Kinetic2012-01-15

well i have not have not had much time because of school. but yes i do have something new coming out.

Kinetic (author)2012-01-15

Thanks! And where have you been???

tom tom go (author)2012-01-15

Very cool idea!!!! if you would be able to fix the remaning problems this, would be the first turret machinegun :D!! great jop and please post when you have time.

Kinetic (author)tom tom go2012-01-15

Thanks! I am going to post this, seeing that I have fixed most of the problems and maxed out the range to around 40ft, but because the Hammer is the gun's main limitation, I am going to work on a V.2 after I have posted this one.

About This Instructable




Bio: Sometimes it takes a man to push beyond what he thinks is possible before he realizes that possibility is a mere conception of the mind ... More »
More by Kinetic:The Kinno-2: A Semi-Automatic K'nex GunThe Kinno-1: K'nex Semi Automatic Rifle (preview)The Kinetic Sling Pistol (KIC2 contest entry)
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