Gas Operating Ammo Feeder (Semi Auto)

MRR · Mon Mar 02, 2009 1:33 pm

This is my idea of a gas operating ammo feeder.

Well it's nothing new (many weapon use it --> Ak47, BAR...) but I was asking myself if it works on a pneumatic or if someone already build something similar :evil3: (Yes, I used the search function).

The "moving tee" only has to move about 2cm to make the ammo (marble) drop into the barrel.

Last weekend I already build a self closing piston valve with a spring and it turned out so well that I don't want to change the valve itself.

psycix · Mon Mar 02, 2009 1:42 pm

Isnt this called a blowback bolt?
It is possible but it may require some tweaking in order to work.

MRR · Mon Mar 02, 2009 1:51 pm

I had the idea when I blew up a homemade silencer, so the potential is there.

I think the problems are:
>construction of a light piston that glides easy in the housing
>the moving tee should glide easy but seal well
>the return spring shouldn't be to strong or to weak
>the position of the pressure catch without loosing performance
>the size of the holes in the pressure catch

yap, a lot of tweaking

POLAND_SPUD · Mon Mar 02, 2009 1:57 pm

the same designs like this appears every 2 or 3 months... it won't work becasue spudguns use realtively low pressures (500 psi or so) when compared to firearms (20 000 psi)

instead you can use an air cylinder hooked up to the chamber to get the same effect... Several people have built a gun based on this principle and it works... check mine it should clear thing up --> http://www.spudfiles.com/forums/i-has-s ... 16872.html

THUNDERLORD · Mon Mar 02, 2009 2:10 pm

It probably has potential.
Sure, a firearm has more PSI's but the firearm piston on an AK for example has large vent holes and a small piston diameter.
Judgement _Arms or "the Judge" experimented with a similar idea I believe.

...And I'm dreaming up a similar idea myself now except the chamber pressure(air reservoir) itself would push the plunger back loading(very similarly to your diagram) and THEN pressing the piston valve's pilot (trigger) also...

Problem I had was that as soon as fired the chamber pressure drops(moving the mag block)... BUT now I am thinking the piston could hold (lock) the magazine in the proper position since the piston remains open until the shot is clear of the muzzle...

Good idea IMO... Now, please try it out and let us know!

8)

MRR · Mon Mar 02, 2009 2:22 pm

@POLAND_SPUD
I saw your diagram and thought, wouldn't it be easier to build a chamber sealer and connect the piston in the green housing with the pilot chamber?

The spring would release the "blow barrel" a little before the main chamber opens.

@THUNDERLORD
I will sure try it and if it doesn't work I have some parts to lay on stock.

POLAND_SPUD · Mon Mar 02, 2009 2:50 pm

@mrr why would you do it ?? care to elaborate ??

in fact inertia and friction slows down the air cylinder so the bolt opens after the whole air in the chamber is gone

MRR · Mon Mar 02, 2009 3:14 pm

Yea, it's more tricky than I guessed.

Otherwise there would be a lot more semi / auto on this website.

Hubb · Mon Mar 02, 2009 3:19 pm

A lot of people say that this will not generate enough pressure to cycle a bolt. IDK, I've never tried it, but I've never seen a working one either, so I am somewhat inclined to believe the masses.

But, that's not stopping you from making it work. Go ahead and get it to work.

POLAND_SPUD · Mon Mar 02, 2009 3:42 pm

@mrr mine works well and it's easy to build...

the design proved to be good... and in fact I am surprised that since I posted it no one has tried to build something similar...

MRR · Mon Mar 02, 2009 3:54 pm

Maybe because your diagram is a little confusing .

A little bigger and slower animation would help.

I understood it but only after watching it several times.

....or did I !?

ALIHISGREAT · Mon Mar 02, 2009 4:06 pm

MRR wrote:Maybe because your diagram is a little confusing .

A little bigger and slower animation would help.

I understood it but only after watching it several times.

....or did I !?

i wasn't confused

or at least i think i wasn't confused...

ok now i'm confused.

POLAND_SPUD · Mon Mar 02, 2009 4:06 pm

the main and the most important part is the 5 way valve... it can be only in two positions - either it fills the gun (while exhausting air from the air cylinder or vice versa

when you press the trigger you press it for maybe 0.2 second but that gives enough time for the gun to fire then the air cylinder retracts and one marble falls into the barrel.. when you depress the trigger the bolt moves forward loading the ammo and the gun is now ready to be fired again

you can use a 3 way valve instead of a 5 way valve but then a single acting air cylinder would have to be hooked directly to the chamber
it's all very simple and straight forward... take your time analising the diagram and the thread you'd be amazed when you realize how easy it is

EDIT
lol is it really so difficult to understand ??

ALIHISGREAT · Mon Mar 02, 2009 4:12 pm

nah, i was just kidding, i got it after watching a few cycles

i think Poland's method is probably better than the gas operated system.

jackssmirkingrevenge · Tue Mar 03, 2009 1:05 am

My FX Monsoon has a conceptually similar system:

The white section of piping around the barrel is part of a coaxial piston, when air exits the muzzle it pushes on the black part at the front of the white tube, pushing the whole assembly back and recocking the trigger/cycling the mag via the rod attached to the brass end of the piston.

I had the idea when I blew up a homemade silencer, so the potential is there.

Essentially, the FX has a silencer with a "moving wall" so to speak, it is this which recocks the mechanism. It works at 1,500-3000 psi, it could potentially be applied to spudguns but the key would be to have a large piston surface area to maximise force as we're limited with pressure.

Gas Operating Ammo Feeder (Semi Auto)

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