The below video details the process used to make a type of machine gun for use with plastic airsoft pellets. This particular type of design is known as a Cloud BBMG. It has an incredible rate of fire, in excess of 50 rounds per second on a full charge of compressed air. This is a real airsoft gun, easily capable of 350fps muzzle velocities. It should be handled with as much care as any other airsoft gun, and the same protective safety gear is required when in use – protective mask, safety glasses, etc…
This machine gun has no moving parts to feed pellets into the barrel, but instead functions on the principles of differential gas pressures. When the trigger is pulled it allows high pressure air into the reservoir that contains the airsoft pellets. The jet of air forces the pellets to bounce around at random while at the same time increasing the internal pressure of the reservoir. Because the barrel is a clear opening from the reservoir to the comparatively lower pressure of the atmosphere outside of the gun, the gas escapes though the barrel while at the same time sucking pellets in with it. Because there are no mechanical parts that take time to cycle as they would in a standard machine gun, the rate at which pellets can enter the barrel and fire from the gun is virtually unlimited.
The air chambers may be increased in size in order to increase the duration of fire. As it is in the video, this machine gun is capable of about 5 seconds of constant firing at 60psi, which equates to about 2-300 pellets fired.
The cost of this build is right around $50. Not bad at all.
Parts List:
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4′ of 2″ pressure rated sch40 PVC
4′ of 1.25″ pressure rated sch40 PVC
2″ end caps x2
2″ 90 degree elbow
2″ 90 degree street elbow
1.25″ end caps x3
1.25″ couplings x2
1.25″x0.5″ threaded reducer
0.5″ threaded plug
6mm ID x 3′ aluminum tube (Alternately a 6mm ID steel automotive brake line my be used)
Rubber tire valve
Air compressor blower valve w/ threaded ends
Close brass pipe nipple – to fit blower valve
Hose fittings – to fit blower valve – x2
1′ air compressor hose – matched to hose fittings
Hose straps – for compressor hose – x2
Large hose straps
1″ foam pipe insulation – or a wood block fitted for chamber support
Hi, I just wanted to ask you… What inner diameter does the air compressor hose have? Please reply me, thanks. Daladirn
I use a 1/4″ line.
were do u get the parts i cant find them any where
Hey man, it’s me again.
… How long does the gun stay pressured, with the pressure that can shoot BBs (I mean with the tank that you have in the video – 2″)?? I wanna build one too, but I will change the design a bit. Thanks for reply. Daladirn (BTW sry for my english, I’m czech 
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Ye…you’ve got it in the text on the end
sry i wasn’t paying attention to that… but thanks. 
Man, that social media floater on the left blocks part of the video…is there a way you can make it closeable so we can see the whole screen?
Thanks….(oh, and your pop-bottle machine gun….well, lets just say airsoft pellets have now become a budget item
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Hi mike,
That’s the first time I’ve gotten that complaint about the media box. It doesn’t block anything when I’m on my widescreen monitor, it must only get in the way on standard or smaller screens. I’ll see if I can adjust it. Thanks for your comment
Hello, I have just completed a prototype of the minigun you showed on youtube. I have completed a tank that will easily hold 100 psi and give me several good bursts. However, when I fire the gun the BBs dont always shoot out. This wastes significant air pressure and makes it a bit unreliable. I noticed in your videos both with the long barrel and the bottle gun that every time you fired it a steady stream of rounds came out. My question is how do I correct my design? I can only see a few solutions. 1 make a smaller chamber. 2 extend the brake line further into the chamber. or 3, I simply dont have enough air pressure to deliver a constant stream, although this one seems unlikely. I would appreciate some help on this as I hope to design a version that is both easy to re pressurize and fires reliably.
Thanks, this is really a genius idea and I would love to perfect it.
Try using more or less BB’s in the chamber and see if that helps. If using a brake line for the barrel, leave the flared end on where the BB’s feed into it.
I have had the chamber mostly full as well as almost empty, I did some test firing from a full chamber and fired it off a air pump until there were only a handfull in the chamber and it did not seem to improve that much during the course of shooting. I am using 7mm brake line and the flared end is inside the chamber. However, I dont think my brake line extends as far into the chamber as the one you used in the bottle gun. Could that be the cause? Also, I have tried both .12 bbs and .25 bbs, so I dont think the weight affects it too much.
It could be that the air is not being fed into the chamber at a high enough volume to properly disturb the pellets and get them moving around. It could also be that the angle that the air is coming in from is not ideal to get them moving. Try holding the gun upside down and at various angles until you get a consistent rate of fire. If that works, rotate the barrel so that the valve is in the position that it was in for the best consistency.
it will work better if you use a smaller ammunition chamber
Ok, I am gonna fiddle with it this weekend to find out what works. I am also considering using a paintball co2 tank with a regulator as the air supply. Any obvious problems with that method? I have found a regulator that will work just wondering if you have tried this yet.
CO2 is not safe to use in PVC. It gets way too cold as it is released from the tank which makes the PVC brittle.