Make an Airsoft Machine Gun from a Soda Bottle

Several months ago I posted a project showing how to make a 'cloud' BB machine gun with a built in air supply out of PVC. That project, while very entertaining, cost $50 in parts and took several hours to complete. More recently I have resumed experimenting with BB machine gun designs with the goal of making them as inexpensive and easy to build as possible. The model that is made in the above video can be assembled in under 5 minutes, uses only four parts, and costs a total of about $15. If you have not seen my previous BB machine gun project you can take a look at it by clicking This Link.

This airsoft gun is a bullpup design, meaning that the pellets enter the barrel from behind the trigger. The machine gun works because as the bottle is pressurized the only way for the air to escape is through the barrel. That escaping air sucks pellets up and out with it like a high velocity vacuum. The rate of fire that can be achieved through such a design is spectacular, in excess of 50 rounds per second. The estimated FPS using a 6" long barrel is 250 when the bottle is fed with air at 100 PSI. If a longer barrel is used much higher velocities can be achieved.

Parts Required:
  • Soda Bottle
  • 7mm x 6" Automotive Brake Line
  • 1/4" Quick Release Air Compressor Fitting
  • Air Compressor Blow Gun

  • Drill & Drill Bits
  • Hot Glue Gun
  • Air Compressor

The only downside to this particular machine gun is that it must be plugged directly into an air compressor line to fire. Fortunately, there are several modifications to this project that remove the need for a constant connection to an air compressor, such as a backpack mounted air tank. A flamethrower style backpack tank version will be featured in my next video, in addition to a modification that requires no access to pressurized air whatsoever, and will cost even less than the featured model.

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Until next time,
<p>I'm doing something similar- I'm just using canned air instead of a compressor so I can easily take it to wars. My main worry is how long the gun will last before it breaks due to wear-and-tear. Should I reinforce it with wood to keep it functional, or should I remake it, but use pvc instead of the bottle?</p>
<p>just finished it- thanks Nighthawk for the instructable! I'll post one of my modded ones here :)</p>
I love this and will build with with my nephews . Thanks for helping to get them excited about making things.
I love to hear people wanting to help kids get into creating things. Have fun! Don't forget the safety glasses!
<p>NightHawk- I'm wondering as to the placement of the air blower. Does the position matter? Thx</p>
We did use the safety glasses and it worked out fine.
<p>Um, would you possibly be able to post a link to where you got the blowgun? I cant find that type anywhere...</p>
<p>go to a hardware/auto parts store</p>
<p>Awesome toy! I couldn't wait for the auto parts store to open, so I substituted the brake line with a 9/32 brass tube 12&quot; long (K &amp; S part #132). I used a plain rubber grommet to hold it in place....no glue required. These are available at most Ace hardware stores and/or hobby shops. If you think about it, the air pressure is only acting on the surface area of the end of the tube to push it out....a very small area. The most ingenious part is that the incoming air agitates the ammo and keeps it feeding the barrel....no bends needed. I rigged up a leftover Ballon Time helium tank for the air supply. I had to drill out the check valve to get it to accept air....great fun!!! I found the blow gun at Harbour Freight. This a great harassment tool for predators.</p><p>John</p>
<p>will it take down pigeons?</p>
<p>We can't find a straight </p><ul> <br><li>7mm x 6&quot; Automotive Brake Line<li> online, any ideas on how to get one?</ul>
<p>awesome post!. </p><p>I am working on a diy shotgun at worldpremierairsoftcenter.com</p><p>also doing a diy sniper rifle and bunkers = )</p>
<p>tried it on my friends it worked like hell...... :)</p>
<p>it is epic</p>
<p>Made it and it works like... like... like a bought one!</p>
If i used a co2 bike pump and plugged it into the blowgun in replacement of the air compressor, would it work?
If you used a longer sized bottle, would you need a longer sized brake line to accommodate?
Would this still work if I made a hole in the back and put my blowgun into the hole at the back of the bottle?? <br>
great build. Do you have any ideas where to get the parts though bunnings ,auto place?? i'm not sure if not do you know any other parts you could use as replacements easier found. Thanks
I got an idea for a more portable supply. No doubt a lot of viewers who watch this also play paintball, like me. If they have a 48ci 3000psiCompressed Air/Nitrogen Tank or better, they could hook up their feed line to the compressor blower tool. Most people who play with Compressed/N2 air use waistband or backpack harnesses with a slinky hose running to the gun. Just more ideas... LOL.... Have fun guys and remember safety first!!!
Here's an idea: Take a pump and a small air tank, combine it with the air switch and bottle- voila! - DIY airsoft shotgun.
nice. like the guns in the game fallen earth. <br>
Using your design I modifed an ammo box to build a Browing M1919 thanks for the idea.
I had an idea, what if I used pvc instead of the pop bottle and made the gun look however I wanted. Would it still work do you think?
Yes, that will work.
In your backpack airtank video was the shooting shown all the tank could manage?
i mean NightHawkInLight. (&quot;&quot;) (*&lt;*) (&quot;&quot;)
Thanks! Good to hear
I'm using a tank i bought online for the air supply. (3 gallons)
I must admit, i am a HUGE fan of your work.
A couple of ideas came to mind after watching. Could you bend the brake line so that it feed from the bottom of the bottle? This might improve the total number of bb's you can shoot before needing to reload. Also, you could replace the brake line with a stiff hose or plastic tube, if you could find one just the right size.
or you could try and add some kind of hopper on, say, the top of the bottle when holding it in firing position.
If you bend the brake line it will change shape around the curve and the pellets will no longer fit through it.
Dude, what is in that target!?<br>
It's corn starch sandwiched between aluminum foil and the cardboard box. I have it in there to give a better effect when the pellets hit..
I like it. Might steal that idea for my Knex guns, when im showing them off to my mates!
I made one that uses a 2-Liter bottle and a ball pump connected to the original bottle instead of a compressor or backpack, and it's light, stylish,and very functional! You hold it like darth maul's lightsaber; the &quot;blowgun&quot; (nozzle) is between the two.
awesome ^^ <br>i am new to this site and i have a little problem where to get the break line is it in carpenter or ........
It's a brake line, not break. They can be found in any auto parts store.
thank you but is there any place other than auto store
Awesome!! Saw this vid first on Right this minute on national tv !!!!! When i saw it, i was thinking...&quot;hmmmm that's such an Intructable kind of project&quot;!! and i was right!! too cool!
Sure enough
have you tried puting more than one barrel on the front so it can shot more
My 7 yr old son is FASCINATED...awesome instructable.
Why thank you
Instead of the Brake Line, would it be possible to use an actual barrel from an airsoft gun? Or is the clearance that the Brake Line provides necessary for the BB's to get sucked through?
An airsoft barrel will work fine.
Got bored and whipped one of these together this afternoon... then another one. Love the simplicity of it, and the way it scatters airsoft pellets all over the back yard. Looking forward to your take on a backpack tank, because the necessity of being hooked to the air compressor is about the only thing that keeps this from perfection.
I just published the new video with the backpack modification to my YouTube channel. I'll try to get it posted here within the week, but you can go see it now if you don't want to wait.