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Gas Assisted Recoil prototype

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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Gas Assisted Recoil prototype

Unread postAuthor: judgment_arms » Sat Aug 18, 2007 3:46 pm

Judgment Arms,
Gas Assisted Recoil operation prototype: G.A.R. 1

Background:
After the failure of the Wookie gun I decided that blow-back, at least pure blow-back, wouldn’t work on a low-pressure platform. So I decided to look-in to other firearm operating systems, the recoil operation of the Ma Duce and the 1919 seemed like a good choice, but after some thinking I realized that the recoil generated by most air cannon was nothing compared to even a .30-06 let alone the .50BMG (duh), especially considering the fact that I was going by paintball regulation velocity’s (230fps for cannon, 295-300fps for paintball guns) at 230fps the1oz NERF football that the cannon was going to shoot would have little if any recoil at all, let alone a .68cal paintball at 300fps.
So something had to be done to increase recoil, or at least increase the rearward movement, so after a little thinking it hit me: what if you vent some of the gas off the barrel part way down the barrel into a gas cylinder that moves the barrel backwards?
Enter the Gas Assisted Recoil system:

About the G.A.R. 1 (pronounced “Gar” like the fish):
This prototype was built out of scrap to see if there’s any probability of this working.

Unfortunately this prototype doesn’t work, I used the pilot valve off the Wookie gun, which no longer functions… but I feel with a few modifications and a better valve it has a chance.

In theory, if all went per plan, it should function like this:
1. Bolt is pulled back and a round is placed in the breach.
2. Pressure chamber is charged.
3. Bolt is closed and locked to breach.
4. Valve is opened and air goes up through bolt in to the breach which sends the projectile down the barrel.
5. Projectile passes barrel ports and firing gases are vented into barrel cylinder.
6. Gases force barrel piston back as projectile leaves muzzle.
7. Gas system and recoil work in tandem to force barrel and bolt back.
8. After 1 inch or so of rearward travel bolt unlocks from breach.
9. Bolt continues rearward and barrel returns forwards
10. Ready to reload

Any advice or questions?

Here’s the pictures:
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Attachments
gas-recoil004.jpg
gas-recoil005.jpg
Next two pictures are close-ups of the bolt to breach lock.
gas-recoil001.jpg
Bolt all the way back.
gas-recoil008.jpg
Barrel all the way back.
gas-recoil009.jpg
Bolt halfway through recoil, bolt is now unlocked from barrel.
gas-recoil010.jpg
Barrel halfway through recoil.
gas-recoil011.jpg
Close up of the bolt and the bolt to breach lock.
gas-recoil012.jpg
Close up of the charge handle and barrel guide.
gas-recoil000.jpg
And now the prototype G.A.R., here’s a large view of the prototype with labels to explain it.
GAS-RECOIL013.JPG
If you don’t have Power Point, here’s a series of images that you should be able to figure it out from (note that the gun displayed differs from the prototype):
gas-recoil.zip
If you have Microsoft Power Point here is a slide show that explains how it should work, (note that the gun displayed differs from the prototype):
(118.13 KiB) Downloaded 66 times
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Unread postAuthor: Hailfire753 » Sat Aug 18, 2007 3:54 pm

WOW!! :shock: Quite a novel idea, never seen anything like this before!
Now get the prototype working!!
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Unread postAuthor: Acdcmonkey1991 » Sat Aug 18, 2007 3:59 pm

Dude, this is so awesome, I can't wait for the working prototype. This is truly innovative.
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Unread postAuthor: judgment_arms » Sat Aug 18, 2007 3:59 pm

Hailfire753 wrote:...Now get the prototype working!!


Now I remember what I was supposed to be doing!!!!
Dang nab it, been sittin’ here tryin’ to figure out what it was I was goin’ to do after I finished posting this! :)
I’m going to take the valve off the wookie gun and put it on this, the main piston valve that is.
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Unread postAuthor: Hailfire753 » Sat Aug 18, 2007 4:15 pm

Lol, glad that helped!

I was looking for a solution for a quick breach-loading cartrage potato gun, and I believe that this could be it. It may be a little complicated for me, though.
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Unread postAuthor: bassmaster1228 » Sat Aug 18, 2007 4:20 pm

thats genius :D

i like how it says magic valve :lol:
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Unread postAuthor: judgment_arms » Sat Aug 18, 2007 4:35 pm

bassmaster1228 wrote:thats genius :D

i like how it says magic valve :lol:


You know why it’s magic? ‘couse it works! :lol:
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Unread postAuthor: Suppressive Fire » Sat Aug 18, 2007 6:09 pm

I've been gone for a while but I'm going to guess that the diagram I sent you sparked your intrest a while back.
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Unread postAuthor: potatoflinger » Sat Aug 18, 2007 6:14 pm

That looks amazing, can't wait to see the finished product!
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Unread postAuthor: wannabie » Sat Aug 18, 2007 6:31 pm

WOW man thats cool looking lol.

what kind of ROF do you expect on the finished product? :P
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Unread postAuthor: judgment_arms » Sat Aug 18, 2007 7:42 pm

Suppressive Fire, no offence but I had all but forgotten about you diagram, the reason I ask was because I wanted to check out the competition. :)

Wannabie, if you talking about the GAR maybe 10 rounds per minute as the GAR is only a single shot.
Otherwise I don’t know, and I won’t know until I get this prototype to work.
But for the auto-cannon I’m shooting for 450-500 rpm range
For the LMG 600-950rpm range
For the HMG 800-1200rpm range
And the combat rifle, well that’s going to be a half-auto.
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Unread postAuthor: jackssmirkingrevenge » Sat Aug 18, 2007 9:33 pm

It looks good on paper but I have my doubts as to how much bleeding from the barrel will work at spudgun pressures. Firearms that use this system typically generate at least 30,000 psi, nowhere near spudgun pressures.

For this to work well you're going to need a large chamber volume, high flow valve and a sufficiently long barrel to retain the pressure long enough to allow the piston to work. Remember, you've increased the area availiable for the air to work on but you've also added to the weight of the bolt.
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Unread postAuthor: From_Hamsterdam » Sat Aug 18, 2007 10:16 pm

if i were you i would take out the holes that vent to the atmosphere in the recoil thingy. This would be more efficient because you probably loose enough pressure out the barrel.

you already have a large recoil piston so you will not need as much pressure because it is acting over a larger area.
remember psi= pounds per square inch

like jack mentioned you should improve the barrel length, chamber size and add a better valve.
Reduce the weight and friction of any moving parts as much as possible.
it may also help to use heavier ammo with a tighter fit or go up to a higher pressures.
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Unread postAuthor: judgment_arms » Sat Aug 18, 2007 10:23 pm

How’d I know you were going to burst my bubble?

Yeah, I know about the pressure deference, but I figured that it made more since than pure recoil operation in the small arms…

I’ve been thinking about this for a long while, it seems to me that this is the best chance of getting something to work, with out using external cylinders powered buy air other than the used to fire, my goal being to have an auto-cannon that runs of an operating system similar to standard firearms, other that a chain gun.


Okay now, I have a question:
After looking over my plans (which are mostly still in my head) I realized that the gas cylinder on the GAR 1 was made wrong, if you look at the pictures of the charge handle/barrel guide area that grove is in the cylinder, between that grove, and the utter lack of seals, the gas cylinder might as well not be there and just have a ported barrel. This is what happens when you rush perfection…

Do I try and make the GAR1 work or do I just go strait to the finished product, a 1.50cal auto-cannon?

With the 1.50cal I could use a solid lead slug if need be to get the recoil part to work, plus with NERF footballs, which fit really tight, they will create a good gas seal which gives the gas system a better chance of working, plus when I shoot NERFs out of my Bazooka I can feel the recoil.
But all have to buy a lot of stuff, and if it doesn’t work it’s all that money down the drain.

If I just fix the GAR 1 it’ll save money, but for all the work, am I just polishing a turd?


Edit:
Buy the time I got all this typed another person already posted.
Like I said, I screwed up the gas cylinder.
you already have a large recoil piston so you will not need as much pressure because it is acting over a larger area.
remember psi= pounds per square inch


Yeah, I would make the cylinder bigger but it would require more reservoir volume. But any way that’s what gives me hope that this might work, but I can’t quite tell what the light at the end of the tunnel is…:)

like jack mentioned you should improve the barrel length, chamber size and add a better valve.



[quote]
Reduce the weight and friction of any moving parts as much as possible.
it may also help to use heavier ammo with a tighter fit or go up to a higher pressures.
[quote]

I had so much grease on the moving parts it wasn’t funny, parts are as light as possible, I’m trying to avoid having to use heave projectiles as I now live in a semi-residential area…
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Unread postAuthor: From_Hamsterdam » Sun Aug 19, 2007 12:37 am

good on yay, i thought i should mention those things just in case. I like your design it reminds me of those automatic 40 mm grenade launchers.

any idea how/if you are going to make detachable mags?
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