Introduction: Knex M4 Carbine (True Trigger)

Picture of Knex M4 Carbine (True Trigger)

A working Knex M4. Fires using a new sear system that allows for better firing. NOT A BLOCK TRIGGER, TRUE TRIGGER SYSTEM!!! Fires approximately 50 feet, much more if you add more rubber bands, can handle a lot. Single shot only, but can be adapted into a magazine type gun quite easily. I will follow up with SOPMOD extras if someone else doesn't first. Sorry for the blurry pics, I need a new camera...

(Most counts are an approximate, I just took a quick count)
Green rods: 100
White rods: 75
Blue rods: 21 + 1 bendable
Yellow rods: 4 + 2 bendable
Red rods: 2
Gray rods: 26 + 1 black one (firing pin)
Gray connectors: 70
White connectors: 4
White "Snowflake" connectors: 27
Red connectors: 33
Green connectors: 110
Yellow connectors: 61
Blue "Snowflake" connectors: 10
Purple connectors: 4
Gray gears: 2
Tan clips: 4
Blue clips: 1
Y-shaped things: 8
Hinges: 3
U part of joint: 1

Step 1: Front Handgrip

Picture of Front Handgrip

This is the front handgrip, one distinctive feature of the M4. Assemble in order, follow the directions EXACTLY. READ THE NOTES. THEY WILL HELP YOU FIGURE THIS OUT. Something may seem like it changed, but it is probably the other end. This was an extremely difficult part to photograph, so sorry if it's a little confusing. Last revised 11/29/2008.

Picture 1: Expand this out until it is 12 long on each level, 24 long total
Picture 4: The rods don't actually fully snap into a place, however, they are wedged in there as show. Therefore, they will make a soft click if they're in place, and will slide smoothly back and forth.
Picture 5 & 8: These pictures are at opposite ends of the barrel. The orange pieces are snapped on the same way at both ends here
Picture 11: This is just a ramrod, do not add this if you plan on using a magazine system with this gun because it effectively plugs the barrel
Picture 14: The gray connectors between the white snowflake and orange connector can be cut; you can cut the tops off of them, because this is where the magwell will eventually go.
Pictures 15 &16: This is just a suggested barrel design, i was almost out of pieces so whatever i had i used for it, feel free to make a better barrel.

Pictures 4, 5, 9, 10, 11, 12, and 13 are the FIRING END of the gun
Pictures 6 - 8 are the BODY END of the gun.

Step 2: Upper Reciever

Picture of Upper Reciever

The upper reciever portion of the M4. The light blue rod on the back IS one of the bendable blue rods which are very rare; I only have 4 of them from one set. You can make it a straight magazine like the Vietnam era guns, and that would probably be the best way to make a working magazine.

Step 3: Carrying Handle

Picture of Carrying Handle

The distinctive carrying handle for the M4.
PLEASE READ: In the middle, it should not be a white snowflake, it should be a yellow "half snowflake." This allows you to look down the valley of surrounding snowflakes to actually use the sights

Step 4: Lower Reciever

Picture of Lower Reciever

The lower receiver portion of the M4. Contains the true trigger portion, and the sear catch. I took pictures from only one side, but it is exactly the same on the other side.
Picture 2: When referring to the triple greens snapped onto the yellow rod, after a few shots, the top part of the middle one will snap off. It's nothing to be concerned about, just realize that it will happen.

Step 5: Firing Pin and Charging Handle

Picture of Firing Pin and Charging Handle

Firing pin and charging handle.

NOTE: PLEASE READ:!!!!The firing pin only has ONE blue connector, NOT two as it shows in the pictures. I took the pictures then realized that it was wrong when I was putting it together.

You should duct tape the part of the firing pin where it goes hinge half-tan connector-blue connector, I didn't to show what it looked like and because I'm out of duct tape. Also, it wouldn't hurt to have all black rods here (they're stronger) because of the stress that gets put on this portion of the gun.

Step 6: Stock

Picture of Stock

I only took one picture of the stock. all across the top, it should be solid, "5-across," so the charging handle slides on it smoothly.

Step 7: Assembly

Picture of Assembly

Assembly for the entire thing. Note the placement of the multiple rubberbands.


nawien01 (author)2012-06-26

can som1 help me.

im stuck by pic 14, 15 and 16

killersir751 (author)2011-07-22

"not block trigger."
All triggers block some kind of firing system, making it a block trigger.

apples!!!!! (author)killersir7512011-07-23

The concept of a sears is different than that of the typical 'block trigger', because it catches the ram instead of blocking it from the front. Believe me, if you had been around in 2008 on this site you would refer only to KillerK style triggers as 'block' triggers and nothing else, because so many were posted that, though others technically block, anything else was considered far too advanced to be lumped with block triggers. It's a trigger type, not an overall classification.

killersir751 (author)apples!!!!!2011-07-23

The trigger piece still BLOCKS a piece from moving though.

apples!!!!! (author)killersir7512011-07-23

You're missing the point.

killersir751 (author)apples!!!!!2011-07-27

Which is..?

apples!!!!! (author)killersir7512011-07-27

There are specific names given to specific things sometimes. "Block trigger" is the name we have given to a connector(usually orange) that is centered onto the side of the main barrel and acts as a gate that lifts in an arced path to move out of the rams path. Best example- KillerK's original pistol. That is what we call a "block trigger". This is not a "block trigger", this is a "sears catch", which snags the rear and of the ram and holds onto it. You can look at everything and find similarities but it is the differences that define.

killersir751 (author)apples!!!!!2011-07-28

You are also missing my point.
Every kind of trigger either catches or stops something. The trigger mechanism BLOCKS a piece from moving and hitting the bullet/firing rubber bands.
When you pull the trigger, it releases the firing mechansim and fires the ammunition that the gun uses.

apples!!!!! (author)killersir7512011-07-28

Oh my goodness child, I'm not an imbecile. I understand this full well, but that does not change the fact that different trigger types have different names. "Block trigger" is a name.

killersir751 (author)apples!!!!!2011-07-31

I know it's a name, but technically, all triggers are block triggers.

apples!!!!! (author)killersir7512011-07-31

Yes, they are, but that does not mean that it is a "Block trigger". I'm repeating what I'm saying over and over and you're just throwing the same thing at me without grasping my point. It is a trigger that blocks, but it is not a bloody "block trigger". This uses a Sears, which, although blocks, is a very different system. I really can't keep saying this lol.

Oblivitus (author)2008-08-03

I knew you would say that. And I also know the next thing you will say. XP

apples!!!!! (author)Oblivitus2011-04-24

I didn't say anything for almost two years, so I doubt that ;P

Oblivitus (author)apples!!!!!2011-04-24

Time is not my master! (trying to imitate my sense of humor at 17, I'm finding it difficult, so maybe it is)

apples!!!!! (author)Oblivitus2011-04-24

Time has definitely mastered you.

Oblivitus (author)apples!!!!!2011-04-25

Nooooo! I want to be a timelord like doctor who.

apples!!!!! (author)Oblivitus2011-04-28

You can try, child(even though I'm younger than you). However...resistance is futile.

Oblivitus (author)apples!!!!!2011-04-28

How long do think it'll take for those apples to rot? Wahaha.

apples!!!!! (author)Oblivitus2011-04-30

They went rotten long ago.

DracoUltima (author)2010-12-09

Sorry, not to disappoint everyone, but I built put on the maximum number of bands that the firing pin can hold and the gun only got to 25 feet. If you want to prove me wrong go ahead and post a video. Sheesh, I hate it when people lie about range just to get views.....

nightfox939 (author)DracoUltima2010-12-09

I'm really sorry you can't get it to shoot any farther. To be honest, my shots with around 45-50 feet or so are a complete ideal case, firing about 40 degrees up angle. Also, those are with the red length rods; heavy enough to not be affected by air resistance slowing them down, but also not so long that they yaw in midair. Also, after I tried to add some more bands after that 50 foot shot, it did break. So my claim of more distance is probably an exaggeration. And I can try to post a video, but it might take some time; with the combination of finals week, having to repair the gun quite substantially, and the cold MN winter, I'm not sure if I'll have the willpower to make a video. Thanks for making it though!

Cheezpaper (author)2010-07-12

Man, you're a genius. Making an M4 SOPMOD anytime soon? But did you have to buy multiple sets to make this? I'm buying new ones anyway, so any suggestions as to what sets to buy? ( btw when I finish this, I'mma mod it to shoot batteries or toothpicks and display it on my shelf.)

nightfox939 (author)Cheezpaper2010-07-13

Thanks, glad you think it's cool. And I've been collecting sets since I was a little kid, so I guess I really can't recommend any sets in particular. Most of the roller coaster sets I had a lot of fun with, and you get a lot of pieces for the money you spend, assuming you're buying new. But the best place to find large quantities for cheap is garage sales and thrift stores, without a doubt. And I did have plans for the SOPMOD addition, but I've been really busy with the combination of college and working... But with summer, I'm thinking about delving back into Knex for a bit and with people showing interest, I might get around to it. I'll post it for sure if I make it... Again, thanks, and happy building!

uberrobodude (author)2010-06-29

im making a m16a4 and its supposed to have a bendy clip. it works, but needs tape.

chopstx (author)2010-01-06

Very realistic!

Well, except for the colors lol.

juneapaluna (author)2009-10-05

This gun is huge. I have built it but cannot make the trigger work. It won't hold the ram back at all, please help and explain to me what could be wrong or how this trigger works. - Thanks.

nightfox939 (author)juneapaluna2009-10-05

Well, if you've ever seen an airsoft gun, it's essentially similar. The three yellow pieces clipped together should pop up and hold the ram back. (Make sure you have rubber bands to pull the trigger mechanism back) When you pull the trigger, it should rotate the yellow pieces so the ram slides off, and by the power of the rubber bands and snaps the ram forward to shoot.

TedWard{} (author)2009-09-07

in pic 14 the grey rod with lots of grey peices on, how does that get attached to main front grip?

nightfox939 (author)TedWard{}2009-09-07

From step 2, take those pieces that are mirrors of each other, and the purple/blue connector combo - that snaps to the middle gray rod on the foregrip, and the white and yellow connectors on that gray rod with all the gray connectors; they snap to various rods on the piece from step 2. Make sense? (I guess look VERY closely at step 7 too, particularly pics 2-6)

IcyHutch (author)2009-07-13

so wait if i add a working mag do i use ramrod shown in pic 11?

nightfox939 (author)IcyHutch2009-07-15

no, you shouldn't add the ramrod. However, you cant build the end of the barrel either with a working mag

hippos are dangerous (author)2008-07-04

what is the blue rod connected to the gray rod supposed to do?

its the firing pin that strikes the ammo

TOMNDAN (author)apples!!!!!2009-06-28

in pic 7 how do you get the rods to stick out like that

nightfox939 (author)TOMNDAN2009-06-28

They're not actually snapped in to anything, they're just sort of "seated" in the channels, so they slide really easily, but don't really provide ANY sort of strength

ILIKEPIE333 (author)2009-04-12

the trigger's in an akward place, maybe if you move the handle....(wink, wink, nudge, nudge).....

j-chode! (author)ILIKEPIE3332009-05-28

say n'more ;)

bluestripe (author)2008-08-04

doesnt the stock look like its from a m16 instead of a m4 ive made a m4 collapsable stock out of knex for this gun ille post it next week

apples!!!!! (author)bluestripe2008-08-06

Actually, that is what I thought at first, but then I realized that it is an M4 Carbine, and that the stock is pretty accurate to that. And about the collapsable stock....I kinda beat ya to it lol. Posted pics three weeks ago...

bluestripe (author)apples!!!!!2008-08-07

where are your pictures can u post a likk cos i want to see if its like mine

apples!!!!! (author)bluestripe2008-08-07

My "likk"s are on this instructables comments. Go to "view all comments" at the botton of the page, and scroll down. You'll see them.

bluestripe (author)apples!!!!!2008-08-08

i ment to say "links" i saw the pictures and but its ok but it doesnt look as good as mine hears some pictures its about 6 pieces thick and is strong therse a picture of my removable mag there aswel

apples!!!!! (author)bluestripe2008-08-08

Yeah, that looks pretty good, but it doesn't look like it adjusts. Mine had the little mechanism(like the real one) that you push up on and slide the whole thing back to make it larger. No offense, but it looks like it's a little flimsy. The detatchable mag looks like the one in the ible though. I gave mine one as well, but it actually worked.

bluestripe (author)apples!!!!!2008-08-09

It does ajust in the 3rd picture but the stock in the third picture isnt what its like now it moves on the blue rod on the gun and the yellow rod on the stock like ,now it looks like the 1st picture but has the ajustable thing and im making the catch thing like the real one and it isnt a little flimsy the stoch is held on with 7 blue rods and the stock itsself is solid at 6 pieces thick all around and i made the gun stronger by adding more pieces and the magazine is the same as the original gun but is detachable and it works

apples!!!!! (author)bluestripe2008-08-09

Ironic how the third picture is hidden and unviewable to me, so could you repost the third?. Well, about the mag: I know it's fake. I looked at it, and it has a yellow connector facing into the mag, and the red connectors facing in. Meaning no loading. You also didn't change the front barrel, meaning that if the mag worked, you'd never get a shot out because of the fact that that there is too much empty space from the mag to the front barrel, so they don't line up. You have to change the front barrel to make it work.

bluestripe (author)apples!!!!!2009-03-13

yes i know that it doesnt work ,i build the guns then if they are good i take all the moving/working parts out and fill it up solid so it is stronger and then i add extras like the removable mag, working m4 stock and other stuff i got into airsoft aswell so i decided to put a airsoft gearbox into a knex g36cits not finnished yet, the 3rd picture is here aswell

apples!!!!! (author)bluestripe2009-04-11

Ok, I see the stock now, but I made mine to have an extending mechanism similar to the real thing, not just looks. I might rebuild this to have a better mag with no pusher, but I don't know if I can get to it with the amount of time I have, along with other projects I am working on.

GEORGE41708 (author)bluestripe2009-01-04


KillerRazor (author)2009-02-01

I tried this gun a long time ago, but the gun kept breaking :( Would anyone have any ideas what went wrong?

nightfox939 (author)KillerRazor2009-02-01

Well, what kept breaking? Even a general location would be nice, because there are definitely some parts that are more prone to breaking than others

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