Gas gun loading on a spudgun?

[noob of noobs]

Okay, so due to new new parental restrictions involving the power of my work, I'm going to try to focus more on a higher rate of fire. So I'm going to try to build an automatic paintball gun.

The valve will be similar to the one in this thread: http://www.spudfiles.com/forums/semi-au ... 15627.html The valve and airsource though isn't what I'm worried about.

The reloading mechanism is what I'm in question about. After looking at gas guns ( http://science.howstuffworks.com/machine-gun7.htm ) I was wondering if you could apply similar technology to a paintball gun. Bassicaly, the difference would be that instead of pushing the gun's bolt back, the piston would push back a hopper so that one paintball could fall into a hole in the barrel. The hopper would then be pushed back away from the hole by a spring.
The picture should explain things a bit more lucidly...

So what do you think? All comments are welcome.

[trollhameran]

The picture doesn't really show how it fires to clearly, but the loading looks good, should work, perhaps I can suggest using a larger opening than you need for the ammo to fall into because then it will be easier for the ammo to drop in while the whole thing is moving, which will allow a higher rate of fire without the ammo getting jammed.

[POLAND_SPUD]

I had a similar idea sometime ago... the only difference is that I am planing to use an air cylinder to do the job...

EDIT
Pics added..... (sorry for using MSPaint )

It's almost as simple as it can be.
The design requires a single acting air cylinder and a 3 way valve. The idea is that the 3 way valve fills the gun and the air cylinder (as they are joined toghether).

The air cylinder pushes the bolt forward loading new ammo and closing the breach.
When the 3 way valve pilots the gun the spring inside an air cylinder pulls the bolt back and new ammo falls from the hopper.

When the trigger is depresed (the 3 way valve switches to filling) the whole cycle repeats



Your design is very unlikely to work properly. People had serious problems with simple blowback bolts.

In your design you want air to move the whole hopper.
The hopper (+ ammo) is going to be very heavy when compared with a design where there is just a bolt to be moved. Even if it cycled properly there would be about 0.5 kg of plastic and ammo moving forward and backward at the same rate as your planed ROF and that isn't going to improve accuracy

I think you should read JSR's thread on his blowback gun (on failure of the design ) Then you'd better understand why your design is not going to work

[trollhameran]

Thats a very clever design Poland, I like it.

[jackssmirkingrevenge]

Bleeding air from the barrel to cycle the action will not work in a 150psi spudgun. Remember that assault rifles that use this system usually generate in excess of 40,000psi of pressure that provides the impetus for the cycling to happen.

Recently I took apart my FX Monsoon semi-auto air rifle:



What it does is use the muzzle blast within the suppressor tube to push back a piston around the barrel. Again though, below 1500 psi it will not cycle. What you want for lower pressures is either a blow-forward bolt, or using direct blowback, have a browse through the forum using the search function

[Leonard]

Another quick little thing i want to add. Moving the whole magazine each shot will result in terrible accuracy (gun shaking) and the cylinder that will contain the air that will push the spring is dead space considering you could go without it.

[noob of noobs]

@ ALL: Blech, thanks. I'm not very knowledgable in firearms and such, and just thought this might work here. Well, back to the drawing board...
Thanks for your time.