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my new and first pneumatic rifle

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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my new and first pneumatic rifle

Unread postAuthor: john bunsenburner » Thu Oct 23, 2008 3:12 pm

i am trying to build a rather strong accurate air powered pellet gun. i have pretty much access to nearly no materials here in switzerland. i will make a gun stock from woad and i want to ty to make the gun look real. i developed a trigger system (i included a diagram). my only problem is the air source i want to have several shots befor ehaving to fill up the air tank. on the other hand i do not want to spend money for a big compressor nor do i want to carry around a huge heavy 500psi tank or nything. plese give me some advice.
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Unread postAuthor: ALIHISGREAT » Thu Oct 23, 2008 3:17 pm

you can attach the diagram using the attachment tool at the bottom of the posting page.
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diagram

Unread postAuthor: john bunsenburner » Thu Oct 23, 2008 3:27 pm

i think i now managed to post the diagram
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Attachments
valve.jpg
this is the diagram, i know its not very good so email me with questions
valve.jpg (13.37 KiB) Viewed 671 times
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Re: my new and first pneumatic rifle

Unread postAuthor: Ragnarok » Thu Oct 23, 2008 3:37 pm

So you want a
- High powered pneumatic rifle that gets lots of shots
- But is portable, without high pressure tanks or compressors.

These goals are somewhat contradictory. There are compromises, but you can't have both.

If you want power and lots of shots, that takes lots of stored pneumatic energy. To have that stored energy, you need lots of air at high pressures. Simple physics, energy can't come from nowhere.
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Does that thing kinda look like a big cat to you?
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Unread postAuthor: john bunsenburner » Thu Oct 23, 2008 3:45 pm

im ok with a compressor or air tank or both but in a contry wer a ball valve costs 50$ stuff isnt cheep also i do not want a huge hard to carry around tank more a smaller tank that is safe, iv blown things up in my face before i dont need it again!
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Unread postAuthor: Gippeto » Thu Oct 23, 2008 4:13 pm

A metal (copper?) gun, with a valved (small ball valve) and regulated CO2 supply is my recommendation.

Can you get CO2 in Switzerland?

What is YOUR definition of accurate?

You say "pellet gun", do you have a barrel (preferably rifled) and ammunition at hand to start with?
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Unread postAuthor: john bunsenburner » Fri Oct 24, 2008 1:19 am

the thing about the ball valve is that i dont like the speed it opens at, ccurate means i can hit a target the size of a coke can from 50meters. i have made bullets and pellets before, thats not my problem. i want to use a smooth bore because it is impossible to get a rifled barrel here with out the police tracking you down. CO2 is a problem i can get it but ist really expensive(500 to 800$ for the bottle plus regulator and only 50bar preasure). for any other pressurized gasses i need a licence.paintball is also problematic in switzerland you need to register any paintball guns you own, have to own a liecence and have to be other 18 so i will not be able to get co2 from there i hope thats info helps. the valve i desighned is supposed to open extremly fast. it will be made up of a peice of metal of the exact diameter of the barrrel but will be a bit longer at the bottom part so it is diagnal wehn in the barrel. it will have a hinge at the top end. at the bottom end of this peice of metal will be a little extension which will hook up to the trigger. when the trigger is pulled the air presure will push the piece of metal up and go into the barrel to shoot the pellet.
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Unread postAuthor: jackssmirkingrevenge » Fri Oct 24, 2008 4:39 am

In my opinion, if you give up on the idea of having more than one shot per fill and buy yourself a relatively cheap mountain bike shock absorber pump and charge your launcher to 300-400 psi for every shot, then your project is more realstic as a goal and will be cheaper and simpler to build.

If you don't want bother with pumping, all you need is
an old fridge ;)
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Unread postAuthor: john bunsenburner » Fri Oct 24, 2008 4:49 am

what bout having one of those small car tire compressors in my back pach, hook it up to the gun and gun it on some batteries!
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Unread postAuthor: jackssmirkingrevenge » Fri Oct 24, 2008 5:23 am

john bunsenburner wrote:what bout having one of those small car tire compressors in my back pach, hook it up to the gun and gun it on some batteries!


That would only work with some serious modifications to the compressor, ie drastic improvement in cooling - fans, heat sinks, encasing it in an oil bath etc. - to stop it from burning out, as well as significantly uprating the motor to increase the rather pathetic flow to practical level.

In short, not worth it.

If you're going to have a back pack, it might as well be an air tank ;)
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Re: my new and first pneumatic rifle

Unread postAuthor: socoj2 » Fri Oct 24, 2008 9:11 am

Ragnarok wrote:So you want a
- High powered pneumatic rifle that gets lots of shots
- But is portable, without high pressure tanks or compressors.

These goals are somewhat contradictory. There are compromises, but you can't have both.

If you want power and lots of shots, that takes lots of stored pneumatic energy. To have that stored energy, you need lots of air at high pressures. Simple physics, energy can't come from nowhere.


Look at SCBA tanks or Paintball HPA tanks...

The Paintball tanks go up to 120 cuI @ 4500 PSI. the SCBA are much larger @ 4500PSI.

If you are using 500 PSI and a schrader you should get a lot of shots out of one of these.
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Unread postAuthor: Gippeto » Fri Oct 24, 2008 9:17 am

I didn't mean to use a ball valve as the main valve.

I meant to use the ball valve for filling the chamber of the gun, a piston valve would be my choice for the main valve.

As Jack says, if you give up the multiple shots per fill part, things become much simpler (and less costly).

Pressure is key, and those 12v compressors will not be nearly as good as a shock pump or home made stirrup pump. (or fridge compressor and storage tank :) )
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Unread postAuthor: john bunsenburner » Fri Oct 24, 2008 2:21 pm

i do not see the prob with milti shots per fill...how come it is so hard?
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Re: my new and first pneumatic rifle

Unread postAuthor: jrrdw » Fri Oct 24, 2008 2:45 pm

john bunsenburner wrote:i am trying to build a rather strong accurate air powered pellet gun. i have pretty much access to nearly no materials here in switzerland. i will make a gun stock from woad and i want to ty to make the gun look real. i developed a trigger system (i included a diagram). my only problem is the air source i want to have several shots befor ehaving to fill up the air tank. on the other hand i do not want to spend money for a big compressor nor do i want to carry around a huge heavy 500psi tank or nything. plese give me some advice.


Buy a pellet rifle! :wink:

Study the BBMG's in that section of the forums and you will get the idea of why it's a hard thing to give advice on what your asking for. Study, then ask.... :D

Welcome to Spudfiles.
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Unread postAuthor: Gippeto » Fri Oct 24, 2008 7:20 pm

I don't think you truly understand what you are asking for. But here goes. :)

Multiple shots per fill can be accomplished in a couple of ways.

1) Pressure tank separated from the chamber by a valve. Open the valve to charge the chamber, then close the valve to isolate the pressure tank. Repeat for each shot. Use a piston valve for the main valve of the gun. (this is what I suggested on my first post)

2) Hammer valve. This is a valve which "dumps" a certain amount of air from a pressure tank/reservoir behind the projectile. It is more complex than a piston valve, and requires several accurately made moving parts.

3) BBMG. Dump air through a vortex block, it pushes bb's out of the barrel. Low power, but very high rate of fire, coupled with a very high rate of air consumption.

If you click on my sig at the bottom of this post, you can see some of what is involved in a hammer valve and trigger mechanism.

What tools do you have access to?
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