Make an Airsoft Machine Gun From a Soda Bottle





Introduction: Make an Airsoft Machine Gun From a Soda Bottle

About: I like turning boring things into awesome things! Usually on video.
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.

Please remember as always to share this article with others on Facebook and Twitter, and if you really want to support my projects, submit this article to other sharing sites sites such as Reddit and Digg. To be the first to know about my new projects you can also subscribe to my YouTube Channel.

Until next time,
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    80 Discussions

    Is there anything i can use to substitute the brake line?

    So I made one this morning using a root beer bottle and a hard plastic straw that was the right size for the bb's, and of course my air compressor. Even with the scavenged parts, this is SO MUCH FUN!!!! Thank you.

    I made this gun for my airsoft loving friends birthday. I put 2 guns on a camera tripod. It was by far the best gift. Thank you for this great instructable

    15 20:06.jpg

    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?

    1 reply

    I love this and will build with with my nephews . Thanks for helping to get them excited about making things.

    3 replies

    I love to hear people wanting to help kids get into creating things. Have fun! Don't forget the safety glasses!

    Um, would you possibly be able to post a link to where you got the blowgun? I cant find that type anywhere...

    1 reply

    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" long (K & S part #132). I used a plain rubber grommet to hold it in 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 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.


    We can't find a straight

    • 7mm x 6" Automotive Brake Line
    • online, any ideas on how to get one?

    awesome post!.

    I am working on a diy shotgun at

    also doing a diy sniper rifle and bunkers = )

    Made it and it works like... like... like a bought one!

    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?