Introduction: K'nex MP5

Picture of K'nex MP5

TGKT entry - This is my K'nex MP5 and one of my favourite real-life weapons of all time. It features a true trigger, 15+ round mag, full stock, and a rugged construction. The gun has yet to misfire (the bullet always leaves the barrel) and has fair range (30-45 ft).

In the instructable there is no assembly step as I assemble it as you build each main part. Follow sticky notes for the tricky spots before asking questions.


-Small,compact, and sturdy
-True trigger
-Large magazine capacity
-Good range
-Consistant accuracy


-Not good for long range shots

Step 1: Magazine and Barrel

Picture of Magazine and Barrel

Pic 1 - Build x2
Pic 2 - Add white rods onto ONE of the two panels made in pic 1
Pic 3 - Another view of pic 2
Pic 4 - Make all of these
Pic 5 - Slide them onto the corresponding rods
Pic 6 - Another view of pic 5
Pic 7 - Attach the red connector here
Pic 8 - Get the second panel ready
Pic 9 - All attached

Step 2: Trigger

Picture of Trigger

Pic 1 - Trigger
Pic 2 - Different view
Pic 3 - Place it in the gun like so (leave it loosely in there for now)

Step 3: Outer Body

Picture of Outer Body

Pic 1 - Make this x2
Pic 2 - Attach to both sides
Pic 3 - Attached
Pic 4 - Trigger goes between these yellows

Step 4: Front Barrel

Picture of Front Barrel

Pic 1 - Make this
Pic 2 - Attach to the front of the gun
Pic 3 - Different view
Pic 4 - yet another view

Step 5: Foregrip and Muzzle

Picture of Foregrip and Muzzle

The muzzle functions as a safety for the gun. It will block any bullet fire out. Simply remove when ready to fire.

Pic 1 - Completed Foregrip
Pic 2 - Different view
Pic 3 - Another view
Pic 4 - Yet another view
Pic 5 - Ready to attach
Pic 6 - Attached
Pic 7 - Other side attached
Pic 8 - Build the muzzle
Pic 9 - Attach it
Pic 10 - What you should have so far

Step 6: Handle and Trigger Guard

Picture of Handle and Trigger Guard

Pic 1 - Finished product
Pic 2 - Make everything seen here x1
Pic 3 - Attach
Pic 4 - Attach
Pic 5 - Ready to go onto gun
Pic 6 - Trigger guard is attached
Pic 7 - Line up the handle
Pic 8 - Attach
Pic 9 - What you've got so far

Step 7: Stock

Picture of Stock

A very sturdy, solid stock...

Pic 1 - Finished product
Pic 2 - Make this x2
Pic 3 - Make this x2
Pic 4 - Make this x1
Pic 5 - Make this x1
Pic 6 - Attach blue rods where shown
Pic 7 - Attach layer
Pic 8 - After layer
Pic 9 - After layer
Pic 10 - And this is the last layer
Pic 11 - read note
Pic 12 - read note
Pic 13 - Ready to attach bendy rods
Pic 14 - Attached
Pic 15 - Ready to attach the stock to the rest of the gun
Pic 16 - Attached



Important step... This keeps the ram from pointing down and hitting the magazine parts.

Pic 1 - Pull off this green connector
Pic 2 - As shown here
Pic 3 - As shown here put a green rod inside
Pic 4 - Inside and you're good
Pic 5 - Close it all up and you're great

Step 9: Mag Push, Firing Pin, Rubber Bands

Picture of Mag Push, Firing Pin, Rubber Bands
Rubber band placement on the ram rod is key...

Pic 1 - Build and find these items
Pic 2 - This is another mag pushed that works a little better than the weird looking one
Pic 3 - Trigger rubber band (A little bit tighter than normal)
Pic 4 - Mag push goes in here
Pic 5 - Rubber band placement for the mag push
Pic 6 - Ram rod goes in here
Pic 7 - It's in with a little force

  • Pic 8 - Ram rod rubber band. It's on that blue rod I mentiond earlier. You could put it on other places but they have to be pulling from below the level of the ram rod, otherwise it will be levered down and hit the internals of the gun (Very low chance of happening). I advise using the spots provided in the picture and in the sticky notes to avoid problems. I will post a video on this. It's a very small problem (it only happened once) but this is just to avoid that.

Step 10: Loading

Picture of Loading

Pic 1 - Ammunition
Pic 2 - Load like so

To fire once loaded, pull back the ram untill the trigger clicks, then pull the trigger. Repeat untill ammunition is depleted then do pic 2 procedure and reapeat this procedure.

Pic 3 - Have fun and don't shoot anything unprepared to be shot at


2000smartkid (author)2012-09-03

I have built all 5 of your guns, and when i get my youtube account in another year, i will post them on there. They are awesome guns!

I don't think I will post them, but they are awesome guns. :)

tarantulas1 (author)2012-06-26

And btw great gun.

tarantulas1 (author)2012-06-25

Could you please add a piece count for this K'nex model?

mr. 707 (author)2012-06-10

i wish that i could build this gun but i dont have enough knex hinges.

ozzters98 (author)2012-04-11

to compecated not to build but to load!!!!!

jonpauljones95 (author)2012-04-10

nice airsoft gun and cool build

seniorpancakeman (author)2011-05-23

all right. so i built it i cocked it filled up the mag pulled the trigger and it fell out of the barrel. woopie!a gun that shoots 4 inches!! the ball joint end keeps on beking off and the mag rod pushes the bullets in half way then it jams. . Either i suck crap with knex or this gun sucks.:(

u probably suck crap with knex1 CAUSE THIS GUN IS AWESOME!


chato56 (author)2011-12-03

what can i use instead of the hinges

Johnhall44 (author)2011-10-18

I had some problems with the trigger but fixed it and made it shoot gray rods

lhodgkiss (author)2011-08-17

i made the model perfectly and followed the instructions except the trigger don't work at all is there anouther one i can use in the model to make it work

Atomic_Sparkz (author)2011-06-24

This gun is BEAST, thanks man

gassybeans (author)2011-06-03

i built this gun and it shot amazingly. nice accuracy!

DJcheerios (author)2009-07-26

I have a problem where the gun somehow shoots multple rounds per shot. Seriously, I loaded it up, cocked it, fired, four rounds came out...

how is that a problem!!?? thats how real mp5ks shoot full auto!

=!snap!= (author)DJcheerios2009-07-28

that is a defult I guess but if it still shootd strong and straight its makes it like almost full auto

AlphOscarAlpha (author)=!snap!=2011-02-02

Huh? How does it being strong make it automatic?

J Moneyman (author)=!snap!=2009-08-06

actually, kindof shotgun effect.

kinexmaster2000 (author)2011-06-02


rootbeer96 (author)2010-08-18

my ram pushs the triger forward

k07n192 (author)rootbeer962010-09-18

use a stronger rubber band on your trigger, or if its strong, pull it further

hope it helped

seniorpancakeman (author)k07n1922011-05-23

thnk u it hlpd me!

is it tape holding the trigger toghether???

LULUS (author)2011-03-25


War Hawk One (author)2011-03-16

you know what I hate about this gun, nothing about the looks but I builded it and you said that the bullet every time leaves the barrel but it doesn't with the one of me. and I do use #64 rubberbands.

Smasher555 (author)2011-01-23

The fore-grip is slanted up a bit to much, but other than that, great gun!

It's a magazine.

kef4444 (author)AlphOscarAlpha2011-02-15


sharpbike123 (author)2011-01-10

man dis is awsome how did you ever fink of dat

AzNaLaNo (author)2010-08-31

do you have to have a slanted magaziine???

matthewb6 (author)2010-06-02

To look at even bigger pictures, if you are using a Windows computer, CTRL plus zooms in, and CTRL minus zooms out. On a Mac, Command plus and minus does the same. P.S.- I am working on this gun at 9:59 PM! Love it so far! Fun and easy to build, can't wait to shoot it. >8D

hungyhipo 2 (author)2010-04-27

you said in pros: "good range"

than in cons you said "not good for long range shots"

Trauts (author)hungyhipo 22010-04-30

 Good range for what it is... that doesn't mean it's a sniper or anything.

james4 (author)2010-04-18

the ram goes right past the f@!$ING trigger!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!11

knexjay (author)2010-04-03

do u need 2 break the white con?

dmytro509 (author)2009-12-26

can you use white rods

ferrari f100 (author)2009-12-20

Quick question what is the mag capacity how many bullets can or should it hold btw the gun is awesome!!

Trauts (author)ferrari f1002009-12-20


grevious (author)2009-01-23

the magazine could have made me cry at how much it broke as i tried to put it together, but i got it :D

Knexwizard (author)grevious2009-12-03

i made it straight then removable

PiTBuLL892 (author)grevious2009-10-21

exact same thing happened to me but i managed to do it

bhuty (author)2009-11-30

could someone post a piece count pppppppllllllllleeeeeeeaaaaasssssssseeeee!!!!!!!!!!!!!!!!!!!!!!!!!

happybirthday (author)2009-10-17

This is Probably the best Mp5 on the site...

ryahe (author)2009-10-16

i made this then changed the mag so its straight, easier to load and shoots just grey connectors without the rod

chazman2 (author)2009-10-10

nice gun, is it a fully auto?

hua_mei65 (author)2009-07-09

one work: awesome. as a first knex gun it is great. it looks like the real thing except for color and some minor details. very reliable, the only problem i have with it is the loading mechanism. the shots seem to have some trouble fitting through the magazine, as it has very little internal support and the rounds can get stuck when the sides bow inwards. i think that i can fix that though. by gluing the blue tip of the trigger to the orange part i was able to use very strong rubber bands and shoot the pieces much farther than before. thanks for the great gun.

hua_mei65 (author)hua_mei652009-07-10

update: although not staying within the bounds or K'nex, i milled a pin out of plexiglass that replaces the grey-orange-blue pin that holds the back. instead of gluing the pieces, i used this new pin. the change is easily apparent, as it easily lets you use a stronger rubber band on the pin and can shoot over 50 feet from the previous 25

mettaurlover (author)hua_mei652009-10-04

you should try making all your pieces out of plexiglass-then you'd have a nearly indestructable gun.

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