Introduction: MBAR: Masterdude Bullpup Assault Rifle

Picture of MBAR: Masterdude Bullpup Assault Rifle

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

Picture of 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

Picture of 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

Picture of 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

Picture of 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

Picture of 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

Picture of 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

Picture of 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

Picture of 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

Picture of 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

Picture of 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.


teddy1998 (author)2010-07-29

whats good power supposed to mean?

Masterdude (author)teddy19982010-07-30

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

teddy1998 (author)Masterdude2010-07-30

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?

shieldsam (author)teddy19982010-11-30

There's no energy mortar in halo

teddy1998 (author)shieldsam2012-06-19

sorry, i was referring to the fuel rod gun.

teddy1998 (author)shieldsam2012-06-19

sorry, i was referring to the fuel rod gun.

teddy1998 (author)shieldsam2012-06-19

sorry, i was referring to the fuel rod gun.

teddy1998 (author)shieldsam2012-06-19

sorry, i was referring to the fuel rod gun.

Millawi Legend (author)teddy19982010-10-17

Well, this isn't an air soft gun, is it?

teddy1998 (author)Millawi Legend2010-10-21

no. it uses kinetic energy while asg's use the energy transferred through a piston or a blast of co2.

Masterdude (author)teddy19982010-07-31

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.

teddy1998 (author)Masterdude2010-10-21

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

DJ Radio (author)2009-12-30

You jerk, I was gonna make something like this.  Now I'm gonna have to scrap it.

DJ Radio (author)DJ Radio2009-12-31

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

Masterdude (author)DJ Radio2011-09-19

Have you posted?

Masterdude (author)2009-12-30

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

knex_mepalm (author)Masterdude2010-03-22

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

Masterdude (author)knex_mepalm2010-03-28

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.

knex_mepalm (author)Masterdude2010-03-31

 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.

Masterdude (author)knex_mepalm2010-03-31

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.

knex_mepalm (author)Masterdude2010-03-31

Oh, I fully modded this to my liking, no pictures soz, and my one has an enclosure which flips open and has a clip, the only bad thing about too strong magazine bands is that it will indefinetly lower your bullet speed and distance causing you to be disappointed in the distance, and friection wears out  the knex, I once had this grey connector which one side got sanded by the tight barrel over time.

Masterdude (author)knex_mepalm2010-04-01

I understand how it might slightly affect the bullet speed and power but I don't think there should be much of a problem of the ammo being sanded down since there is no real barrel in the sense of a tube down which a projectile is propelled. I would also like you to please make a picture of your mod if you wouldn't mind so I could see how some people would prefer the guns to be so I might include such in a new version of the MBAR.

knex_mepalm (author)Masterdude2010-04-01

 My camera broke, but I can explain that your gun is perfect, but i Always mod guns to my liking because It makes me happier to know I still have some imagination, I rarely make guns because I lack the skill to start off with a  base shape but I mod extremely well.

Barris (author)knex_mepalm2011-06-13

same, i made someone elses bolt action sniper look like a compactable grenade laucher, i cracked a broken tv screen wiv it

shieldsam (author)Masterdude2010-11-30

Why not try making a bullpup rifle like this with the removable mag and stuff but with a firing pin instead?

Masterdude (author)shieldsam2010-11-30

I already made the new version but thanks for the feedback. The main problem with me making firing pin weapons is that I'm not good at them. The last time I really made one for an I'ble was my micro or nano uzi which was a couple years ago and was one of my first k'nex I'bles. Lately I've experimented with those designs but they didn't go as well so I think that at least for now I'll continue working with my specialization. However if you know a good firing pin system which works very well then how about posting some images of it and I'll see if I can make something with it.

Raikou-san (author)Masterdude2009-12-31

Maybe add a handle like the knexsayer's?
I know you've been on KI, so you'll know where to look.

Masterdude (author)Raikou-san2009-12-31

I can't find a good image. With all the changes it's hard to get anything done on KI.

Masterdude (author)Raikou-san2010-01-01

The images don't want to show for me.

You have to click the steps in order to make the images apear try clicking 1st step then the 2nd it did that same thing to me.

Never mind. I got it to work. I can't make a handle like that because I don't have the pieces needed.

knexp90 (author)2010-11-07

wish you had a parts list. :0

Masterdude (author)knexp902010-11-08

It would be useful but I'm too lazy. I don't want to take the time to count through all the parts.

rec0n (author)2010-04-22

what rubber bands should I use, and where can I get them?

Masterdude (author)rec0n2010-04-22

Well I just cut some in half and tied them together so they'd fit.

rec0n (author)Masterdude2010-04-22

which should i cut? #32's or # 64's?

Masterdude (author)rec0n2010-04-24

Both work but I think the #64's are stronger.

An Villain (author)2010-03-25


Masterdude (author)2010-02-25

What do you mean? Do you mean how it works or have you made it and it doesn't seem to work semi-auto for you?

Seleziona (author)2010-01-03

is this any good?

Masterdude (author)Seleziona2010-01-03

What do you mean by that?

Seleziona (author)Masterdude2010-01-03

is the mech, the gun any good?

Masterdude (author)Seleziona2010-01-03

The gun is very sturdy, reliable, strong, and accurate if that's what you mean. The mag doesn't jam that often if at all and there is no ram rod to jam the gun. The mechanism has been strengthened so it shouldn't fail although it can be hard to pull the trigger (it's not hair triggered).

Seleziona (author)Masterdude2010-01-04

cool! might build sometime :)

PindaHoofd (author)2009-12-30

I don't like RBG's.
Then kinda suck.

TheDunkis (author)PindaHoofd2009-12-31

Essentially they're mini repeating sling shots. I don't know why they get so much hate. My only problem is that a lot of the mechanisms can't actually hold a lot of power so it would be nice to see one that could.

Masterdude (author)TheDunkis2009-12-31

I'm working on one which would be able to hold a lot more power.

juneapaluna (author)PindaHoofd2009-12-30

It shoots knex... not rubberbands

PindaHoofd (author)juneapaluna2009-12-30


About This Instructable




Bio: 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 ... More »
More by Masterdude:MBSMG-2 BuildMBSMG-2Masterdude Automatic MAC 10
Add instructable to: