MBAR: Masterdude Bullpup Assault Rifle





Introduction: MBAR: Masterdude Bullpup Assault Rifle

About: I make K'nex guns, specializing in semi-automatic, RBG-Slingshot hybrid systems which i use in most of my guns. Note: I am not responsible in any way for any damage, injury, or death caused by my Instructab...

This is a true semi-auto, bullpup rifle that I've made. It uses the same basic concept as my MARs but is bullpup and therefor is stronger but shorter. I also believe this to be the first bullpup semi-auto gun on Instructables.

-Comfortable grip
-Carry handle
-Semi-auto (you choose you ROF)
-Removable mag
-Good power
-Good range
-Trigger guard
-OK looks
-Well balanced weight (makes one-handed shooting easier)

-Can be hard to load at first (but gets easy after some practice)
-Uses quite a lot of parts
-Can be hard to attach mag to gun
-Doesn't have a safety like the MARs do

More Instructables by me.

Note: The first image shows the MBAR with an optional vertical grip.

Step 1: Barrel: Making the Components

Make the following:

Picture 1: Make 3.
Picture 2: Make 2.
Picture 3: Make 14.
Picture 4: Make 14.
Picture 5: Make 14.

Step 2: Barrel: Construction

Follow the images:

Picture 1: Place blue rods as shown.
Picture 2: Place three of the earlier made parts as shown.
Picture 3: Cover as shown.
Picture 4: Add four gray rods the the piece as shown.
Picture 5: Place the earlier made parts as shown.
Picture 6: Now add another piece like the first.
Picture 7: Again add the earlier constructed pieces but with their places switched.
Picture 8: When finished it should look like this.
Picture 9: Attach the two parts you've made so it looks like this.

Step 3: Trigger/Ammo-Feed/Stock: Making the Components

Make the following. Due to the large amount of parts each part will be assigned a letter:

Picture 1: Make 1. (Part A)
Picture 2: Make 1. (Part B)
Picture 3: Make 1. (Part C)
Picture 4: Make 1. (Part D)
Picture 5: Make 2. (Part E)
Picture 6: Make 1. (Part F)
Picture 7: Make 1. (Part G)
Picture 8: Make 1. (Part H)
Picture 9: Make 1. (Part I)
Picture 10: Make 1. (Part J)
Picture 11: Make 1. (Part K)
Picture 12: Make 1. (Part L)
Picture 13: Make 1. (Part M)

Step 4: Trigger/Ammo-Feed/Stock: Construction

Follow the images:

Picture 1: Place white and blue rods on part A.
Picture 2: Add part B and blue and white rods.
Picture 3: Add parts C and E, and add white rods and tan clips.
Picture 4: Add parts D, F, H, I, J, K, and then add blue spacers and a green connector.
Picture 5: Add parts E and G, and add tan clips and blue spacers.
Picture 6: Add part L.
Picture 7: Add part M and a blue rod.
Picture 8: Add tan clips.
Picture 9: Add a gray connector, metallic blue clip, and place a white rod as shown.

Step 5: Carry Handle: Construction

Follow the images:

Picture 1: Make this and put aside.
Picture 2: Make these.
Picture 3: Add gray connectors as shown.
Picture 4: Add light gray connectors.
Picture 5: Make 2 of these.
Picture 6: Place them as shown.
Pictures 7-8: Join the 2 components together as shown.
Picture 9: Attach to the gun as shown.
Pictures 10-11: Attached to gun.

Step 6: Magazine: Making the Components

Make the following:

Picture 1: Make 2.
Picture 2: Make 2.
Picture 3: Make 1.
Picture 4: Make 1.

Step 7: Magazine: Construction

Follow the images:

Picture 1: Add white rods.
Picture 2: Add the two earlier made parts.
Picture 3: Cover with the other part.
Picture 4: Finished mag with ammo, ammo pusher, and pin in place.

Step 8: Assembly of the Rifle

Attach the barrel to the rest of the gun so it looks like in the images.

Step 9: Loading and Firing

To load remove the mag and place the pin in the appropriate area. Now place the ammo in the mag. insert the mag into the ammo feed. Next push the white rods in the ammo feed area out to the sides. Hook the rubber bands on the end of the barrel and the trigger spoke. Make sure the rubber bands are on both sides of the ammo. Once all the rubber bands are hooked push the white rods back into the center. Remove the pin. Pull the trigger to fire (in case you didn't figure that out).

Image 1: Ammo.
Image 2: Magazine with ammo.
Image 3: Rubber band hooked on barrel.
Image 4: View of ammo feed when loaded.
Image 5: View of spoke in back when loaded.
Image 6: View of gun with mag.

Warning- This may cause harm or injury if misused. Do not point it at people. I am not responsible for damage, injury, or death caused by this instructable.

Step 10: Optional Additions

You can add a vertical grip as show in image 1. You shouldn't need an instructable to make it.
You can also add my under-barrel grenade launcher.



    • Creative Misuse Contest

      Creative Misuse Contest
    • Stick It! Contest

      Stick It! Contest
    • Game Life Contest

      Game Life Contest

    53 Discussions

    It means that the projectile has a good amount of power/kinetic energy meaning that it could hurt someone and damage some objects.

    are the rounds like single pieces? with tan heads? and an airsoft gun could do better, its faster to reload, hits harder, shoots farther. but i like ur design. maybe something halo next time? assault rifle? energy mortar?

    The ammo is made of multiple pieces which you can see if you look at the other steps. As for airsoft guns, they were specially made to shoot while k'nex were made to be toys to make cars, towers, roller coasters and such things but not guns. This means that they may be good as gun making material but they are not ideal so they may not get the statistics of airsoft guns that easily.

    ok your being oxymoronic. good as gun making material but not so ideal is an oxymoron. (oxymoron is a real word fyi)

    You know what, scratch that, there are some design elements of your gun I don't like, mine will be posted.

    I'm considering making a second upgraded version. Anybody have any requests for what should be upgraded?

    4 replies

     Enclose the shooting mech, and make it "unjammable" by keeping the ammo and the rubber bands in the roughly same area.

    If I enclose the rubber-band spoke, it might be hard to load and what do you mean by  "make it "unjammable" by keeping the ammo and the rubber bands in the roughly same area."? Does it jam because the third white rod on the far right right behind the ammo should prevent it from jamming. If you experience problems please PM me so I can try to fix them.


     Becasue if the ammo slips up it falls out but if you enclose it, like  removable enclosure then you can make sure its' unjammable or ammo doesn't fall out. It may jam because the ammo can easily move around.

    It doesn't move around if the magazine rubberband is strong enough and therefor constantly applies pressure preventing it from falling out. An enclosure which I think you are suggestion might prevent the rubberband from hooking the ammo. I have had more experience with my guns (obviously) and therefor I suggest you use a stronger rubberband which would push the ammo against the white rods hard enough that they would not move easily on their own.