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Reviewers For A Prototype BB Gun Design Needed

This area is for the discussion of BB or airsoft sub machine guns, and or other small arms such as pellets.
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Is It A Phesable Design?

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Reviewers For A Prototype BB Gun Design Needed

Unread postAuthor: cammyd32 » Sun Jun 19, 2011 4:03 pm

After a lot of research on paintball guns and the pop-off and blow forward designs of jsr, I have came up with the following idea, shamefully due to me being pressed for time at the moment I cannot make any snazzy animations or put pictures of the valve here but the chances are I will add them later, for now a sketchup of my entire design will have to do.

This is not just for the valve though, I have also formulated a gun (the model 55 reising) that this design will go into, the gun will be run off propane or green gas, constant flow is not a problem as my valve is quite efficient.
I have only included the bare essentials in the sketchup, that includes the valve itself, the trigger mechanism, and the location of the gas tank (the mag is worked out but due to complexity issues the details are not included in it)

I wish for some of you guys to please tell me what you think about my concept and designs I have drawn them out and are at current awaiting the purchase of building materials, please if you can see any flaws or things I might have missed please post, or if you wish to just make any comment I am all ears.

The design is pretty self explanatory but if you don't understand please ask. :D
Thank you and here is the link:
http://sketchup.google.com/3dwarehouse/details?mid=30657bc8f6c942e7cc6249aa74b2499e&prevstart=0
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reising.png
A preview of my gun-in-progress
Last edited by cammyd32 on Tue Jun 21, 2011 11:36 am, edited 2 times in total.
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Unread postAuthor: Alster370 » Mon Jun 20, 2011 10:52 am

Looks nice, i like the thin metal piece used for the stock.
propane or green gas, constant flow
Does that mean its a combustion? Because when you say constant flow, it would seem more orientated to a pneumatic.
:?
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Unread postAuthor: Doctore » Mon Jun 20, 2011 10:56 am

Quote:
propane or green gas, constant flow
Does that mean its a combustion? Because when you say constant flow, it would seem more orientated to a pneumatic.


some bb guns use green gas as a propellant,same as compressed air.
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Unread postAuthor: Alster370 » Mon Jun 20, 2011 10:58 am

what would be the advantages of using green gas over air?
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Unread postAuthor: jackssmirkingrevenge » Mon Jun 20, 2011 11:04 am

looks pretty and immediately recognisable as the Reising but can't really comment on the mechanism which is the important bit ;)

Alster370 wrote:what would be the advantages of using green gas over air?


At low pressures, propane will liquify allowing you to store more volume, same reason many airguns use CO<sub>2</sub> instead of air.
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Unread postAuthor: cammyd32 » Mon Jun 20, 2011 3:41 pm

Yes jsr and Doctore are correct, the gun is pneumatic and the low liquefying point of green gas or propane means i can store more of it.
Here is the promised link to the valve system, the bits that aren't covered here are covered on jsr's many blow forward threads.
[youtube]http://www.youtube.com/watch?v=MgkCL6sDQlk[/youtube]
btw if you pause the animation at the very beginning the parts of the animation are labeled, due to me overlooking this when I was making it the frame whizzes by in under a second so be quick if you wish too see it!!

A animation of the entire mech is comming soon,
but these thing take time :wink:

Comment much appreciated. :D
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A picture of my Interior mech (gas chamber not included)
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Unread postAuthor: velocity3x » Mon Jun 20, 2011 4:28 pm

cammy,
Have you calculated the bolt spring force that will be necessary to open the valves? If the spring is strong enough to open the valves, I doubt that the gas from the valves will be sufficient to ever completely overcome the spring pressure and move the bolt to the forward position where it can re-engage the sear again.
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Unread postAuthor: warhead052 » Mon Jun 20, 2011 4:32 pm

Also heres another thing, good luck machining it all. Its going to take at least 1 month to get the firing mechanism made, and maybe 2 to get it designed to where its easy to machine. I am no machinist, so I cant say how long it will really take, but it will take awhile to build. And no doubt cost alot.
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Unread postAuthor: jackssmirkingrevenge » Mon Jun 20, 2011 8:21 pm

If you can make it, I think it should work. The hammer valves should prevent it from hanging. Unless you use HPA though, I wouldn't expect great performance, maybe 400 fps for 0.20g airsoft BBs with propane, but if you want it for skirmishing that's perfect.

You're wasting a lot of air cycling the mechanism which is quite high volume, there are more efficient ways of designing it, definitely it would be worth using a single valve - 50% less things to go wrong.
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Unread postAuthor: cammyd32 » Tue Jun 21, 2011 11:17 am

Have you calculated the bolt spring force that will be necessary to open the valves? If the spring is strong enough to open the valves, I doubt that the gas from the valves will be sufficient to ever completely overcome the spring pressure and move the bolt to the forward position where it can re-engage the sear again.

why is that?, the spring will never have to directly push against the force of the hp tank, what I didn't include in the animation was the springs which are pushing the valves shut, the inertia of the spring will be enough to open the valve and keep it open as long as the air pressure hasn't reached pop-off level. once the bolt starts shooting backwards the inertia should be enough to get it too trigger latch point, if not then I will change the location of the trigger sear so it does not have to go so far. hope that has explained that. :)

Also heres another thing, good luck machining it all. Its going to take at least 1 month to get the firing mechanism made, and maybe 2 to get it designed to where its easy to machine. I am no machinist, so I cant say how long it will really take, but it will take awhile to build. And no doubt cost alot.

Machining this is no issue, the entire point of the straight line valve was to make it easily constructible, a steel tube a thick bit of flat sheet metal a few tubes and crap loads of epoxy should make this in a treat, the cost on the other hand is no issue I have a fair bit of funds and this is a long term progect. :)



If you can make it, I think it should work. The hammer valves should prevent it from hanging. Unless you use HPA though, I wouldn't expect great performance, maybe 400 fps for 0.20g airsoft BBs with propane, but if you want it for skirmishing that's perfect.

You're wasting a lot of air cycling the mechanism which is quite high volume, there are more efficient ways of designing it, definitely it would be worth using a single valve - 50% less things to go wrong.

Agreeably the real valve has been carefully worked out to have optimum power for the blow forward chamber, also 400 fps is what I was aiming for as I wish to use this for skirmishing.
Otherwise in my opinion the two valves would increase the performance of the gun, of course there is more to go wrong but if carefully made I think this might stand a good chance of greatly improving performance. :)

The prototype of the valve is coming as soon as I can get an empty large propane tank for an air chamber, as I have no air compressor decent enough to provide a constant stream of air. :D
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Unread postAuthor: jackssmirkingrevenge » Wed Jun 22, 2011 7:02 am

I think performance will be good enough with one valve, and its worth a bit of redesign to keep things simple, plus remember you'll be reducing turbulence and gas consumption.

One thing you might or might not have thought about, how do you cock the bolt for the first shot or in the event of a misfire?
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Unread postAuthor: cammyd32 » Wed Jun 22, 2011 11:22 am

The bolt handle can be attached like so:
sorry the picture is crude, I am working on a detailed animation of the entire guns workings :D
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Crude drawing on paint showing bolt location.
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Unread postAuthor: jackssmirkingrevenge » Wed Jun 22, 2011 11:32 am

Interesting.

If I remember well the Reising bolt handle is similarly very weirdly placed in the underside of the stock beneath the barrel.
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Unread postAuthor: cammyd32 » Wed Jun 22, 2011 11:36 am

Yeah, in my design the cocking bolt will be about where the shell ejection slot is, sort of emerged inside it so the aesthetics are maintained. :)
The slot will be there in my gun but there will be nothing in it apart from the hop-up adjustment screw. :D
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Unread postAuthor: jackssmirkingrevenge » Wed Jun 22, 2011 11:41 am

The M3 greasegun was cocked by inserting a finger into the bolt itelf, no shame in that ;)


By the way, your poll title irks me: http://www.merriam-webster.com/dictionary/feasible
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