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| jackssmirkingrevenge |
 Posted: 06/11/2007 1:47 AM Post subject: preloaded pneumatic cartridge |
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space monkey
Joined: 15 Mar 2007
Posts: 6485
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I downloaded a bunch of WW2 tank documentaries recently, found myself re-watching saving private ryan and digging up medal of honour allied assault, I have to say its re-kindled my interest in making a decent cartridge pneumatic.
As a matter of interest, I hooked up a length of 0.177 barrel to the pneumatic pengun project to see what the power would be like if I made a rifle-sized cartridge, the BB came out with considerable haste but only left a small dent in the bottom of a soup tin so not worthwhile power in my opinion and definitely not enough to cycle the action.
Therefor I concluded that the best course of action would be to scale things up to 3/4" calibre. I want the cartridge to use the same material as the barrel, this would solve alignment issues with "mass" produced cartridges and make fo a sleeker more realistic (to some extent) design. The launcher that would use it would have a spring-loaded bolt that would seat the cartridge in the breech and when it reaches the end of its travel, a pin on the bolt would strike the schrader valve and fire the cart. This would then fire the projectile and blow back the cartridge and bolt, to either recock it ready for a next shot or if a sear wasn't fitted, give full auto action.
The plan therefore is to make the cartridge first, to the design below, and evaluate the power potential. The volume is small but at around 350 psi I'm hoping it will give worthwhile "oomph". Watch this space 
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| Redcoat |
| Posted: 06/11/2007 1:50 AM Post subject: |
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Bobblehead Doll
Joined: 13 Feb 2007
Posts: 843
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that's is a great idea.Are you going to have to build a gun especially for it 
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| jackssmirkingrevenge |
| Posted: 06/11/2007 2:02 AM Post subject: |
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space monkey
Joined: 15 Mar 2007
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| Imperialist1 wrote: | | that's is a great idea.Are you going to have to build a gun especially for it |
Naturally it will have to be a specialised launcher. Given the cartridge dimenstions will be similar to a 20mm cannon round (3/4" calibre is 19.05mm, close enough) I'm thinking it will look something like the Lahti L-39 anti-tank rifle with a similar top-loading gravity fed mag with around 5 carts.
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| wannabie |
| Posted: 06/11/2007 2:03 AM Post subject: |
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Captain
Joined: 15 Apr 2007
Posts: 308
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| love the idea could be usefull just not sure how lol.... BTW how do you get it to 350psi?
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| jackssmirkingrevenge |
| Posted: 06/11/2007 2:06 AM Post subject: |
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space monkey
Joined: 15 Mar 2007
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| wannabie |
| Posted: 06/11/2007 2:14 AM Post subject: |
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Captain
Joined: 15 Apr 2007
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| 350 psi from that !!!!!!!!!!!!! how hard does it get to pump and how long to pump somthing up...
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| Redcoat |
| Posted: 06/11/2007 2:16 AM Post subject: |
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Bobblehead Doll
Joined: 13 Feb 2007
Posts: 843
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he gets 350psi from that from some can-do attitude and some elbow grease.
THat is awesome post it when you're done i cant wait to see it built into that anti-armour gun.Good Luck jack. 
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| A-98 |
| Posted: 06/11/2007 2:22 AM Post subject: |
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Pussy Lover
Joined: 27 Apr 2006
Posts: 907
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| well, if you try to build it, it will A) work, and be astounding or B) it wont work, but it will definitely be interesting. eitherway, it will involve alot of epoxy
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| wannabie |
| Posted: 06/11/2007 2:30 AM Post subject: |
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Captain
Joined: 15 Apr 2007
Posts: 308
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| lol i would never be able to pump it up. Back on topic i would love to see that up and running.
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| Redcoat |
| Posted: 06/11/2007 2:32 AM Post subject: |
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Bobblehead Doll
Joined: 13 Feb 2007
Posts: 843
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| wannabie wrote: | | lol i would never be able to pump it up. |
Neither would i.
Anyway what would the magazine capacity be if you went with the full-auto option?
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| jackssmirkingrevenge |
| Posted: 06/11/2007 2:44 AM Post subject: |
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space monkey
Joined: 15 Mar 2007
Posts: 6485
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| Quote: | | 350 psi from that !!!!!!!!!!!!! how hard does it get to pump and how long to pump somthing up... |
It really isn't that hard provided you use it for reasonably small chambers - I can take my mini-piston to 400 psi in less than a minute.
| Quote: | | well, if you try to build it, it will A) work, and be astounding or B) it wont work, but it will definitely be interesting. eitherway, it will involve alot of epoxy |
I'm pretty sure that the cartridge will work as I've made similar designs before. Also, I'm sure it will have enough power to shoot the projectile and eject the cartridge - if I managed this wit ha combustion, then it should work with a pneumatic. The question is, will it have enough power to push the bolt far back enough to enable it to chamber a new cartridge. If not, I can always make it a straight pull action and manually cycle the bolt for the next round.
and yes, a lot of epoxy
| Quote: | | Anyway what would the magazine capacity be if you went with the full-auto option? |
I doubt i'd have the patience to make more than 5 cartridges so I'm guessing semi-auto is the best idea.
To have an idea of what the mechansim will look like, take a look here
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| A-98 |
| Posted: 06/11/2007 3:08 AM Post subject: |
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Pussy Lover
Joined: 27 Apr 2006
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| Imperialist1 wrote: | | wannabie wrote: | | lol i would never be able to pump it up. |
Neither would i.
Anyway what would the magazine capacity be if you went with the full-auto option? |
actually, if you invest the money in a decent shock pump, it really isnt that hard. i bought one so that i could make a pen-gun for myself, and i can easily get it up to 300+psi without strain. and i aint buff.
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| wannabie |
| Posted: 06/11/2007 3:17 AM Post subject: |
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Captain
Joined: 15 Apr 2007
Posts: 308
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cool
so they are that easy? cool i might have to buy one
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| jackssmirkingrevenge |
| Posted: 06/11/2007 3:42 AM Post subject: |
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space monkey
Joined: 15 Mar 2007
Posts: 6485
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| wannabie wrote: | cool
so they are that easy? cool i might have to buy one |
make sure you can build a spudgun that can take that sort of pressure, 300 psi ain't no joke 
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| wannabie |
| Posted: 06/11/2007 3:52 AM Post subject: |
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Captain
Joined: 15 Apr 2007
Posts: 308
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| yes i will make sure of that i will
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