pneumatic blowback mod for AEGs

Building or modifying BB, Airsoft, and Pellet type of guns. Show off your custom designs, find tips and other discussion. Target practice only!
iknowmy3tables
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Mon Jan 05, 2009 4:51 pm

the following design is adapted from 2 of Antonio's designs
the first one I can't find at the moment I believe it was his design with the hammer valve perpendicular to bolt,

however I also added a second valve and piston thing to help cycle the bolt,
http://www.spudfiles.com/forums/automat ... 13665.html
my experience wit hammer valve and automatic airsoft gun designs back when I was more involved with this forum tell me that the blowback force will probably be too insignificant to cycle the bolt alone, using a separate valve provides much more force because it's like mounting a separated airgun used to cycle, but when they feed off of the same valve the air dumps out the barrel so fast that there is hardly any pressure to cycle the bolt

okay anyways this is what a typical airsoft aeg looks like inside
Image

and this is the mod I proposing
Image
Image
Image

also tell me any of your suggestions for moding an airsoft AEGs to run on air
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jackssmirkingrevenge
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Mon Jan 05, 2009 5:31 pm

Brilliant concept but I don't think that valve arrangement will work, I would go with a single hammer valve feeding directly into the chamber. i modded your diagram just to show the idea, in practice you'd eliminate a lot more dead space.
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iknowmy3tables
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Mon Jan 05, 2009 6:46 pm

I could get the springs to go in place if that's why you don't recomend it, I was ignoring that detail,

you and I both know the difficulty of getting these things to cycle, I never got the thing to cycle even once; ant was able to make his full auto work because it had 2 valves, in practice using 2 valves actually reduces dead space its just wastes more air. In the diagram your suggesting all the air directed on the piston might make it cycle prematurely or if the pathway between the side piston and bolt is larger the air is likely to be dumped out of the barrel quickly and not cycle. When you have 2 valves you can practically think of the 2 valves as being not connected, with all the air from the second valve dedicated to cycling the gun you get more force to ensure the bolt cycles, more force will make it more reliable like long stroke gas pistons on AKs
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Sticky_Tape
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Mon Jan 05, 2009 6:57 pm

I would mae the recoil chamber just as wide as tube the bolt travels in. What I think is have two hammer valves just like antonios stacked tube.
With the recoil cyclinder just above the cylinder that the bolt travles in making for less ''Bending'' forces on the rod that connects the recoil bolt and the fireing bolt. Jack I think your diagram has alot of dead space and wouldn't be too powerful. Actually if you use jacks design you could make it have very little dead space because you wouldn't need the cone part on the fireing bolt.
You can tell how awesome a cannon is by the pressure used.
http://www.spudfiles.com/forums/high-pr ... 12803.html
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raptorforce
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Mon Jan 05, 2009 7:42 pm

there is a pneumatic blowback made by g&g airsoft company but there a bit expenisve about $400
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jackssmirkingrevenge
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Tue Jan 06, 2009 1:16 am

I would make it in such a way that the "hammer" portion is simply a rod that would be of minimum area giving the air little place to push on, and connect the tubing from the valve to the breech in such a way that it doesn't contact the main piston, and leave the cycling completely to the motor.
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ALIHISGREAT
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Tue Jan 06, 2009 2:44 am

Nice idea, but what are you trying to achieve from this design? a higher ROF/cycle rate?
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Necrosis
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Tue Jan 06, 2009 8:28 am

ALIHISGREAT wrote:Nice idea, but what are you trying to achieve from this design? a higher ROF/cycle rate?
I am allmost certain that you'd get a really really really big significance in the speed at wich the BB leaves the barrel....
Allthough we may be the most intelligent creature on this planet, we are also the most inconsistent.
To find peace within our existence we often create a logic that endangers our lives.
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ALIHISGREAT
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Tue Jan 06, 2009 12:17 pm

Necrosis wrote:
ALIHISGREAT wrote:Nice idea, but what are you trying to achieve from this design? a higher ROF/cycle rate?
I am allmost certain that you'd get a really really really big significance in the speed at wich the BB leaves the barrel....
yeah but then you couldn't use it for airsoft...
iknowmy3tables
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Tue Jan 06, 2009 4:09 pm

Sticky_Tape wrote:I would mae the recoil chamber just as wide as tube the bolt travels in. What I think is have two hammer valves just like antonios stacked tube.
yes that's exactly what I'm proposing in the diagram
ALIHISGREAT wrote:Nice idea, but what are you trying to achieve from this design? a higher ROF/cycle rate?
you mean from modding an AEG to be pneumatic, well I wouldn't mod a good condition AEG of course but suppose your like me and have broken aegs beyond repair
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ALIHISGREAT
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Tue Jan 06, 2009 4:22 pm

you mean from modding an AEG to be pneumatic, well I wouldn't mod a good condition AEG of course but suppose your like me and have broken aegs beyond repair
ahhh ok! I don't have any broken AEGs lying around because of the stupid VCR act in the Uk... but its a cool idea to convert one into something more powerful :wink:
iknowmy3tables
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Fri Jan 09, 2009 4:34 pm

I just drew this, it's just for a blow forward bolt mod, I'd have to rig it with some valve system if I wanted it to shoot it in full auto or not to drain air when trigger is pulled
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biged
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Sun Jan 11, 2009 4:45 pm

Escort was making a set of "drop in" internals that were being tested a year ago. Have not heard anything new. (Not a picture of the MadBull v2 CO2 gearbox.)

Basically you replace the piston/cylinder set and have a gas line running through the back of the gearbox. If the AEG has a piston/cylinder a conversion could be performed making the gun adjustable up to 500-600 fps.

Here is a picture of the setup in a version 3 gearbox.

Image

Technically it would be a hybrid electric & gas gun. No more broken gearboxes from high stress springs.

///ed///
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