Copperheads new barrel - 4mm bore for biro cartridge darts

Show us your pneumatic spud gun! Discuss pneumatic (compressed gas) powered potato guns and related accessories. Valve types, actuation, pipe, materials, fittings, compressors, safety, gas choices, and more.
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Hotwired
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Tue May 01, 2007 6:14 am

Firstly the 4mm barrels are 60cm fibreglass tent poles with an 8mm OD and a 4mm ID and the yellow coupling used to join them is a cut down and dremel lathed core of one of these:
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A picture walkthrough of the build :wink:

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The darts are the brass nibbed plastic tubes inside ball point pens with the rear end slit a few mm and flared out. They can punch through as many cardboard boxes as you can be bothered to put in front of it or through a 5mm softwood plank :)
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experament-u2
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Tue May 01, 2007 7:05 am

hehehehheheh kool
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zeigs spud
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Tue May 01, 2007 4:23 pm

very nice. looks professionaly great! :D
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pyromaniac
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Tue May 01, 2007 4:26 pm

nice. can you still have its old barrel? or will it be shooting pens forever now.
:pottytrain3:
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chaos
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Tue May 01, 2007 5:02 pm

it must be very fun to cap cans and stuff.....hmmm may i ask you now how you get more than one shot off a fill?

have you though about putting a scope/sight on it?
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jackssmirkingrevenge
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Wed May 02, 2007 3:56 am

Nice, though you probably could have joined a third length of tent pole and have a real high velocity penetrator, you certainly have the spare chamber capacity.
hectmarr wrote:You have to make many weapons, because this field is long and short life
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Hotwired
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Wed May 02, 2007 4:00 am

I can switch barrels on it still, the one I used for the outer shell of this had a tiny dent halfway along so it was pretty crap if I was using tight fitting ammo. It was just lying about so I decided to give it another go :)

I can also do nail darts with tape or unravelled string tails. Theres a number of holes through a 1/2" plank now... and a hole in my celing when I managed to press the trigger instead of the safety :oops:

Chaos I've not made my semi yet, the only hint I'll give is that all you can see on the cannon is all I'm using. Obvious perhaps but sometimes it needs to be said.
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jackssmirkingrevenge
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Wed May 02, 2007 4:47 am

If you only exhaust a small amount of the pilot chamber, the piston will reseal before the chamber has time to empty, not sure if that's what you´re getting at...
hectmarr wrote:You have to make many weapons, because this field is long and short life
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Hotwired
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Wed May 02, 2007 4:56 am

I didn't notice your first post Jack: I already had the 1m copper barrel so it wasn't really possible to attach more poles after it - I have a suspicion the reduction of bore to 4mm is pushing the air towards the speed of sound - definitely a sharpish noise when firing.
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jackssmirkingrevenge
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Wed May 02, 2007 5:01 am

You really should try going for higher pressure, with just 12 inches of barrel at 400 psi I had managed this.

It's a great design and I don't see why it shouldn't hit near-subsonic velocity with light enough ammunition. My only gripe would be the extra pilot volume but I suppose you have to sacrifice some performance for ergonomic´s sake :wink:

edit: another small tip, with higher pressures the pilot blowgun is going to harder to operate, perhaps an actual trigger would be a good idea to spread the weight over your finger and make it less of an effort.
hectmarr wrote:You have to make many weapons, because this field is long and short life
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Hotwired
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Wed May 02, 2007 5:52 am

I can feel the difference between 240psi and 0psi but it doesn't seem to be causing much of a problem - I wear a black cotton glove on my grip hand so my finger slides over the trigger as it's pulled instead of sticking.

A shock pump will be on my shopping list as soon as I find a way to attach it - I'm using a presta valve and shocks take schraders I believe...
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jackssmirkingrevenge
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Wed May 02, 2007 5:57 am

hectmarr wrote:You have to make many weapons, because this field is long and short life
Hawkeye
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Wed May 02, 2007 5:59 am

I guarantee you won't have the patience to pump up a chamber that size with a shock pump. Even topping it up after filling it with a track pump will be an ordeal. Since you are using copper and JFC, why don't you make your own?
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Wed May 02, 2007 6:04 am

Hawkeye wrote:I guarantee you won't have the patience to pump up a chamber that size with a shock pump. Even topping it up after filling it with a track pump will be an ordeal.
Ordeal :shock: come on, where's your cojones? Besides, it's good exercise :D
hectmarr wrote:You have to make many weapons, because this field is long and short life
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Hotwired
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Wed May 02, 2007 11:20 am

Exercise shmexcersice, I do this for the fun of it :wink:

I've already got a couple of those things jack but the bloody things leak like hell :roll:

Maybe they're low quality.
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