Simple machine gun.

[hectmarr]

I am interested in the possibility of shooting 6mm plastic pellets without any
mechanism.
The idea is that the tube that contains the bbs, is hermetically closed
At one end, it's gravity feed.
When air enters, only one bb propels through the firing barrel. All the
Others are driven up into the tube that houses the ammunition.
I did tests and it works correctly, shooting one by one perfectly.
The trick is that since the air that is compressed in the tube that houses the
the bbs, when the barrel has been emptied, it returns mjy quickly
all the bbs and the cycle repeats.
If the bbs loader is open, it does not work because the bbs accelerated by the
gravity does not arrive in time for the next impulse of air.
It is a mechanical resonance system, because the
times of air pulses, about 9 per second, with the rise and fall of the bbs, they are in sync.
The nice thing is that he shoots one at a time.
The fact that they go up, is necessary for only one to come out, and the fact
go down quickly, propelled by the air that reached a certain pressure
in shooting, it is necessary so that you always have a bb available for
the next shot.
It's a "T" machine gun, and it can be built in a couple of hours.
You only need a 3/2 valve, although I didn't have and used a 5/2, working like
3/2. I will leave a video when I do.
The system to activate the solenoid at the desired frequency is a modified servo motor, a push button, and a small li-po battery.
Obviously you can shoot semi-auto too, using the solenoid trigger, so I have two shooting modes. The magazine houses 60 bbs for automatic firing.

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[jackssmirkingrevenge]

Very interesting! I would be worried about the BBs damaging each other in the magazine though, did you verify that they are intact after a few shots?

[hectmarr]

Yes, I have taken into account the point that you make.
The charger cap has a rubber so that the bb that can stick there, is not destroyed. I reuse the same bbs many times, so I know they come out intact.
Keep in mind that the balls fit quite well in the loading tube. This makes the air contained in the upper part of the tube act as a pneumatic spring, because at 10 bar, which is at the pressure that fires the weapon, (maximum pressure that I can subject to the solenoid valve), the balls do not touch the cap, because the air from the upper part cannot pass down so quickly and less when there is air pressure from the firing barrel, which has an oring to prevent the bbs from falling. I could check this using a transparent tube, a hose, to see how it works.
I have added a weight of 4 grams, after introducing the bbs in the loader tube, to make it shoot all the bbs. When there are few left, the route they take is greater, and they do not have time to reach the "T" for the next shot. With this weight of 4 grams, it shoots all.
I have observed that the bbs move all stuck in the tube. In semiautomatic, it sometimes fires two, but only occasionally, an acceptable error if one takes into account that everything is reduced to a simple "T", one outlet for the barrel, another for the entry of compressed air and another for the bbs.
At 9 or 10 bars, it shoots roughly like a green gas marker, enough to play for a while. Maybe I made a nice fairing, machine gun type of the second war or if I replace the engine with a crank, something older, the kind that gives you a handle to shoot.
The design is more exactly like that, as in the drawing. The distance between the oring and the BBs magazine tube ensures that the ammunition exits the barrel. Mechanics taught me that this is always the case. Obviously, I did nothing, just observe how it behaves and put together the "behaviors" that help me to make it work.

Ametralladora simple.png (6.87 KiB) Viewed 10632 times

[hectmarr]

Another option that I like is a double barrel machine gun.
I would only use a 5/2 solenoid valve, but with all its inputs and outputs.
The guns alternate one and one when firing, because a shot occurs
when the solenoid valve is activated and also, when it is
disabled.
With this arrangement, it is possible to double the rate of shots, question
which I don't like very much, but it is possible to reach 25 shots per second, 12
for each barrel, which is what I already tested and it works fine. It's the little video
in my semi-auto hybrid post, talking about a possible hybrid
automatic.
Keeping the rate of fire at 10 per second, each barrel fires
5 per second, which I like, having two chargers of 60 bbs each,
Ammunition autonomy is multiplied to 120 available rounds.
The size of the machine gun is practically unaffected.
It would work fine, because it is the same as I have but using the other input
and 5/2 valve outlet that I currently have plugged.

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[jackssmirkingrevenge]

Nice idea, you could easily make something like the Villar Perosa



The magazine style would fit too!

[hectmarr]

Wow! in love at first sight with this pair of cannons! She had never seen it even in photos. Excellent choice of yours, and I agree that it can be perfectly adapted to the type of machine I designed.
On the other hand, the video is very good, I mean the animations. I already subscribed to that channel on youtube.
First I will make a test run video and then I will see how to do something similar with things around the house. Sure it will take much more time and work than the machine itself, but I think I would like to have something like that, to play with.

[jackssmirkingrevenge]

I think I would like to have something like that, to play with.

As long as you do it safely

[hectmarr]

jajajajaja !!!Yes, I have seen the movie and I never looked at the machine gun. It looks like my nephew when he enters my workshop with his replica, all the wings of my models pierced!

[hectmarr]

Simple machine gun test. At the end of the video, I forgot to extract the steel bolt that acts as a ballast, and it shot out of the tube that contains the ammunition ... thankfully to the right side.
He fired 60 0.23 gram 6mm rounds of airsoft, and I used auto and semi auto mode. The pressure was 7 bar, and the rate of fire was reduced from 12 to 9 rounds per second or so. Sounds good like that.

[farcticox1]

Trouble with rapid fire is the fun is over too quickly

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[hectmarr]

Oh yeah. For this reason I want to modify the grip of the loading tube to change them quickly. I plan to make about 4 or 5 tubes, load them all and take out and put in the gun.

[hectmarr]

This is the electromechanical system, which among several other things also makes this machine gun work.
The servo motor is modified to rotate in one direction freely, I only use the motor and reduction gears. The potentiometer and board with electronic components were removed because they are not needed.
With the number of arms, 2, 3, 4 ... the frequency of shots is modified and in the same way, by varying the speed of the motor (more or less electrical resistance), which is the fine adjustment.
The pushbutton is a good quality limit switch, which is what allows or does not pass current from the battery to the solenoid, 12 vol in this case, from the solenoid valve, and that's it.

[hectmarr]

Installing the two cannons and manufacturing the ammunition magazines.
I'm making 4 long tubes of 70 bbs each, to swap out while shooting. I used small ball valves, I have several, to seal the tube and be able to handle it without the bbs falling. Once fixed on the weapon, by means of a hard rubber tube, which is enough so that it does not get ejected, which has been proven, you open the ball valve and the bbs are introduced into the weapon.
The two neodymium magnets that are seen are so that the steel bolt that works as ballast, (so that it fires all the ammunition), remains protruding when the tube is extracted. Otherwise you have to turn the gun over and it is very uncomfortable.
I also made two curved magazines of 35bbs each, which are smaller, and more in line with the original weapon.
Some photos of what I'm doing ...

[jackssmirkingrevenge]

Nice! It's going to be great seeing it in action with the alternating barrels, especially if the rate of fire is low enough to be able to perceive it.

[hectmarr]

I am going to make a video with a firing rate of no more than 6 per second. I prefer not much speed because everything is clearer to my eyes and ears.
I have also tested a speed twice what I use in video, but only for testing. As I was saying, I prefer a firing rate of about 8 to 10 per second, which is easy to modify with the speed of the servo motor.