Help with my valve/design choice

[jackssmirkingrevenge]

Forgot about this one?

I would sooner forget my first love ;P

we can guide you through this process, or provide links.
Que JSR in 3...2....1...

I think given OP's budget and needs, it might be a little overkill...

The cheapest way of getting high pressure is to build yourself a stirrup pump.
We've got an excellent how-to on those too somewhere..

OK, I'll bite

http://www.spudfiles.com/forums/easy-st ... 13277.html

Alternatively you can buy a 260 psi track pump for less than 50 bucks.

[Andy_]

Low budgets usually take HPA out of the equation.

Are you set on semi-auto or will a single shot high powered pneumatic do?

Have you had any thoughts as to what calibre and sort of ammunition you would use?

Semi-auto would be awesome, but in saying that I don't mind having to manually put another bullet in via the breech loader every shot.

The ID of my barrel will be either 10.88mm or 17.01mm. Depending which copper pipe I choose.
I would love to use marbles but I'm not sure of there exact size yet. I can always cut aluminium rods up to make bullets.

I could also use a steel barrel but I haven't looked into those yet. Is there any benefit of going copper over steel? I know copper would be lighter but weaker also, but does the projectile shoot faster with copper or something?

http://www.spudfiles.com/forums/old-sha ... 17827.html

modifying a QEV ( easy mod) enables it to fire multiple shots from a single chamber.

You'll need less parts:
Chamber, QEV, homemade hammervalve, barrel and... offcourse a filling valve.

The homemade hammervalve consists of a reducer, an O-ring, a small spring and a screw/bolt with a capnut on the end.Also not to difficult to build or hard to come by.

You can then add any type of breechloading method you like.

If you really want to impress I suggest using a blow forward-bolt and a double action trigger.
( pull trigger-hammer builds up tension-hammer releases.Release trigger to reset.)

we can guide you through this process, or provide links.
Que JSR in 3...2....1...


The cheapest way of getting high pressure is to build yourself a stirrup pump.
We've got an excellent how-to on those too somewhere..

This sounds much more convenient than a coaxial copper gun.
I went through the 10000 pages of your shatterhand gun, it is a really nice gun, top job mate. The trigger system is the only thing that confused me

I don't think I'm good enough to make something like that yet



So many different designs and systems, so overwhelming.
Really I just want to build this
- multiple shots per chamber
- bolt action breech loading
- powerful enough to "theoretically" take down small-medium game (I won't be actually doing this)
- has some kind of finger trigger system


Thankyou so much for all your help so far I have really learnt a lot more than just randomly browsing the internet not knowing what to look for

[RBurke83]

Copper has the advantage of being easily soldered to other copper parts, steel on the other hand, can be brazed, but most often thought of as a welding material. I would prefer steel seamless tubing over almost any other material, but it is not readily available where I live like copper, and I haven't bought my arc welder yet... so no, velocity would be the same with virtually any barrel material given the same diameter and smoothness. Multiple shots per chamber while retaining high power is difficult to achieve. You can create a single shot gun with 150 lb/ft muzzle energy quite easily, for reference a .380 handgun has around 200lb/ft of energy.

[jackssmirkingrevenge]

The ID of my barrel will be either 10.88mm or 17.01mm. Depending which copper pipe I choose.
I would love to use marbles but I'm not sure of there exact size yet. I can always cut aluminium rods up to make bullets.

Marbles are poor projectiles, they shatter easily and have poor sectional density. If I was thinking of your theoretical purposes, I would go for a bore of at least 3/4" and make it a shotgun. You compensate for the limited accuracy available to improvised weapons by firing a spread of multiple projectiles, after all high power is nothing if you can't hit anything.

I could also use a steel barrel but I haven't looked into those yet. Is there any benefit of going copper over steel? I know copper would be lighter but weaker also, but does the projectile shoot faster with copper or something?

Steel is stronger but it should make no observable difference in ballistic performance.

Really I just want to build this
- multiple shots per chamber
- bolt action breech loading
- powerful enough to "theoretically" take down small-medium game (I won't be actually doing this)
- has some kind of finger trigger system

I would remove the first criterion given your limited budget and lack of experience. Without a decent high pressure system, you will either get a limited number of anaemic shots, or have a launcher so huge it will need to be mounted on a vehicle.

Go for a single shot launcher, decent chamber size, long barrel and try to find yourself a cheap high pressure source like a fridge compressor or track pump that will do 260 psi, or built your own stirrup pump.



That is what I would be aiming for at this point.

Edit: some advice on making wads for buckshot: http://www.spudfiles.com/forums/bucksho ... 19639.html

[Andy_]

The ID of my barrel will be either 10.88mm or 17.01mm. Depending which copper pipe I choose.
I would love to use marbles but I'm not sure of there exact size yet. I can always cut aluminium rods up to make bullets.

Marbles are poor projectiles, they shatter easily and have poor sectional density. If I was thinking of your theoretical purposes, I would go for a bore of at least 3/4" and make it a shotgun. You compensate for the limited accuracy available to improvised weapons by firing a spread of multiple projectiles, after all high power is nothing if you can't hit anything.

I could also use a steel barrel but I haven't looked into those yet. Is there any benefit of going copper over steel? I know copper would be lighter but weaker also, but does the projectile shoot faster with copper or something?

Steel is stronger but it should make no observable difference in ballistic performance.

Really I just want to build this
- multiple shots per chamber
- bolt action breech loading
- powerful enough to "theoretically" take down small-medium game (I won't be actually doing this)
- has some kind of finger trigger system

I would remove the first criterion given your limited budget and lack of experience. Without a decent high pressure system, you will either get a limited number of anaemic shots, or have a launcher so huge it will need to be mounted on a vehicle.

Go for a single shot launcher, decent chamber size, long barrel and try to find yourself a cheap high pressure source like a fridge compressor or track pump that will do 260 psi, or built your own stirrup pump.



That is what I would be aiming for at this point.

How the flip do you make shotgun shells :0
If I go for a 3/4" (19mm) bore, I won't be able to use copper pipe, I'll have to get steel
I suppose I can sacrifice the semi-auto for now and make another setup later when I have better skill.

also, is this correct?
If so, what can I use for the pressure chamber?

[jackssmirkingrevenge]

How the flip do you make shotgun shells :0

See my edit

If I go for a 3/4" (19mm) bore, I won't be able to use copper pipe, I'll have to get steel

I'm assuming you're in the UK, can't you get 22mm pipe?

I suppose I can sacrifice the semi-auto for now and make another setup later when I have better skill.

Good man.

also, is this correct?

Pretty much, except that what you marked as a schrader valve is actually part of a jubilee clip, the actual schrader is on the other end.

In the case of the launcher illustrated, the QEV is homemade.

If so, what can I use for the pressure chamber?

The design I illustrated uses an old propane tank.

Some other launchers of similar configuration for inspiration:

http://www.spudfiles.com/forums/600-psi ... 17298.html

http://www.spudfiles.com/forums/my-firs ... 23319.html

http://www.spudfiles.com/forums/pac-qev ... 24362.html

http://www.spudfiles.com/forums/my-firs ... 24493.html

http://www.spudfiles.com/forums/italian ... 24046.html

http://www.spudfiles.com/forums/my-new- ... 23248.html

http://www.spudfiles.com/forums/my-firs ... 20928.html

http://www.spudfiles.com/forums/first-f ... 22401.html

http://www.spudfiles.com/forums/3-4-qev-gun-t22193.html

[Andy_]

How the flip do you make shotgun shells :0

See my edit

Ah cool!

If I go for a 3/4" (19mm) bore, I won't be able to use copper pipe, I'll have to get steel

I'm assuming you're in the UK, can't you get 22mm pipe?

I'm from Australia, mate.
G'day

I read somewhere you said UK copper was thin and couldn't handle high pressures, does this also apply to Australia?

also, is this correct?

Pretty much, except that what you marked as a schrader valve is actually part of a jubilee clip, the actual schrader is on the other end.

Oh derp, I see the schrader valve now!

In the case of the launcher illustrated, the QEV is homemade.

If so, what can I use for the pressure chamber?

The design I illustrated uses an old propane tank.

Some other launchers of similar configuration for inspiration:

Ah cool there are a lot of nice cannons out there with some crazy power

I didn't expect my outcome to have half as much power as some of those seem to have!

That power....

[jackssmirkingrevenge]

I'm from Australia, mate.
G'day

Ahhh... hadn't recognised you without the G'day

I read somewhere you said UK copper was thin and couldn't handle high pressures, does this also apply to Australia?

It doesn't matter where copper comes from, rather what it's rated for. Easy to find out.

That power....

Yup... made well, you won't need more than one shot and if you use standard parts and threaded pipe and fittings, it's just a question of screwing the thing together to have a working "chassis".

[Andy_]

Do I have to have a chamber that bloody big?
I could always use a fire extinguisher as a resevoir, attached to a chamber with a ball valve to refill the chamber after every shot

how big does my chamber have to be? I looked at GDDT or whatever it is and well yea.. a lot of data going on there and I have no idea what I'm doing

[jackssmirkingrevenge]

how big does my chamber have to be? I looked at GDDT or whatever it is and well yea.. a lot of data going on there and I have no idea what I'm doing

http://www.spudfiles.com/forums/ggdt-hg ... 23256.html

Decide on what calibre you're going for, what valve you'll be using, barrel length, what sort of pressures you plan on running at and go from there. Generally for higher pressures (I recommend at least 200 psi) you can get away with a chamber roughly the same volume as your barrel.

Remember a smaller chamber is easier and quicker to fill if you're doing it manually, and smaller means quieter if noise is an issue.

[Brian the brain]

As pressure goes up, volume can go down.

Some newbie once made this:
http://www.spudfiles.com/forums/viewtop ... .html#9661



23 bar, copper barrel....short, compact.
Wish I had his skills...

[jackssmirkingrevenge]

Some newbie once made this

I remember that guy, crazy dutsch type obsessed with circumscising his launchers

[DaxSF]

I personally love coaxial designs, I made my own gun a coaxial. I've also experienced a problem many complain on coaxial designs - that they are single shot. I found a really simple solution for that using 16g CO2 cartridges and a cheap CO2 regulator (2 bottles, 1 regulator for $15..). Assuming you already have a dremel (not a must), a saw, a pair of files and a wrench, this build wouldn't cost you more than $20~$30 (unless you add the extra scope and buttpad which together are an additional $80~). Only downside with this exact design, it's pretty !@%#ing time consuming.
It's pretty powerful too, from a 12g cartridge I am getting about 5 consistent shots, at around 750 FPS, and at 160 PSI (from a normal pump) I am getting 550 FPS. I am shooting 0.177 cal (4.5mm) pellets.

Here's what my build looks like:

[Lockednloaded]

I thought those co2 things were just flow regulators, do they regulate to a set pressure for constant flow?

[DaxSF]

I personally bought a pretty cheap one so it closes and opens easily with a knob (the red twisty one). I bet you can find fixed regulated ones on eBay, but they cost quite a bit more than that simple $15 one.