pneumatic pen gun v2 - added video

Miniature guns are novelty custom, unique, and sometime downright crude! Common construction materials often include pill bottles or pens. Show us your work!
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jackssmirkingrevenge
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Sun Dec 28, 2008 7:11 am

Most of you are probably aware of my pneumatic pen-gun, this is an extended version of the same concept. Chamber size is roughly double and barrel length is almost three times that of the original, so it clearly no longer fits in the "pen" category.

I've also used a different piston configuration, with the piston now being solid rubber cut from 1/4" thick sheet as shown below:

Image

Otherwise, construction and materials are the same as the first version, have a look at the how-to here for details.

The idea is to evaluate the power potential of this small (2.5mm, roughly one tenth of an inch) calibre with a reasonably sized barrel and chamber taken to high pressures (300 psi+) and if successful, fabricate a coaxial suppressor and later a pistol grip to enable the unit to be operated in a conventional manner.

So far I've only been able to test it to 150 psi but I should have one of these beto shock pumps on the way, gauge goes up to 400 psi :) so expect significant performance results soon.

How it works:

Image

edit 30/01/2010:

high speed target footage:

[youtube][/youtube]


[youtube][/youtube]


[youtube][/youtube]


[youtube][/youtube]

edit 01/03/2009. damage video:

[youtube][/youtube]

steel bolt section fired at 400 psi at a gamo tin.

Until then, some pics:
Attachments
Barrel, piston and schrader before being epoxied inside the chamber
Barrel, piston and schrader before being epoxied inside the chamber
v2 next to its little brother and an actual pen for scale
v2 next to its little brother and an actual pen for scale
Last edited by jackssmirkingrevenge on Sat Feb 26, 2011 3:40 am, edited 3 times in total.
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Carlman
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Sun Dec 28, 2008 7:15 am

Nice work mate!

But i agree with your fears in the other thread, i think the rubber piston will expand to much when high pressure is applied
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jackssmirkingrevenge
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Sun Dec 28, 2008 9:17 am

Carlman wrote:I think the rubber piston will expand to much when high pressure is applied
It's been fine so far, it's cut fairly roughly so I'm hoping it will be ok. Time will tell, can't wait for that shock pump to arrive.

Brilliant time to visit ebay.co.uk at the moment thanks to the exchange rate :D also bought a CO<sub>2</sub> tyre inflator, expect a machine pistol soon ;)
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ALIHISGREAT
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Sun Dec 28, 2008 9:22 am

jackssmirkingrevenge wrote:
Carlman wrote:I think the rubber piston will expand to much when high pressure is applied
It's been fine so far, it's cut fairly roughly so I'm hoping it will be ok. Time will tell, can't wait for that shock pump to arrive.

Brilliant time to visit ebay.co.uk at the moment thanks to the exchange rate :D also bought a CO<sub>2</sub> tyre inflator, expect a machine pistol soon ;)
thank Gordon :roll: i remember when the £ was 1:2 against the $... happy times... now its just crap against everything.
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Sticky_Tape
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Sun Dec 28, 2008 9:38 am

Video? Nice gun how long is it in inches?
You can tell how awesome a cannon is by the pressure used.
http://www.spudfiles.com/forums/high-pr ... 12803.html
xnt rnm ne z ahtbg
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jackssmirkingrevenge
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Sun Dec 28, 2008 9:55 am

Sticky_Tape wrote:Video? Nice gun how long is it in inches?
Videos will come when I get the shock pump as it's pointless testing damage now. Total length is 38cm, that's just under 15 inches.
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Sticky_Tape
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Sun Dec 28, 2008 11:35 am

It's not pointless it can still do somthing.
You can tell how awesome a cannon is by the pressure used.
http://www.spudfiles.com/forums/high-pr ... 12803.html
xnt rnm ne z ahtbg
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ALIHISGREAT
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Sun Dec 28, 2008 11:41 am

yeah but it will be crap at 150psi.
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Sticky_Tape
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Sun Dec 28, 2008 11:52 am

Ok well I'm sure it will be fun with high pressure.
You can tell how awesome a cannon is by the pressure used.
http://www.spudfiles.com/forums/high-pr ... 12803.html
xnt rnm ne z ahtbg
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jackssmirkingrevenge
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Sat Jan 03, 2009 5:36 am

Got my new pump (modded for comfort as seen is the attached picture) and at 400 psi it's a blast!

[youtube][/youtube]

That's a small section of bolt as ammunition at 400 psi straight through a gamo tin (and the polystyrene backing). It's pretty loud too so a detachable suppressor is on the cards.

Did I mention how much I like this pump :D
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pgv2pump.JPG
pgv2pump.JPG (28.55 KiB) Viewed 4240 times
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ALIHISGREAT
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Sat Jan 03, 2009 6:24 am

nice to see the piston doesn't compress and expand and that shock pump is pretty tasty... maybe i should mod mine too, its got this terrible tiny handle that would be too small for a 5 year old :roll:
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LikimysCrotchus5
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Sat Jan 03, 2009 2:39 pm

Looks nice and promising. Now ill prob get the some 1/4 inch rubber so i can finish my pen gun.

By the way, didnt that leave a hole in your wall?
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jackssmirkingrevenge
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Sat Jan 03, 2009 3:39 pm

LikimysCrotchus5 wrote:Now ill prob get the some 1/4 inch rubber so i can finish my pen gun.
I have to say this piston really is the mutt's nuts, childishly simple to make , so problem with attaching a separate seal, durable and works great at high pressure, unlike the original pengun that leaked above 200 psi and never had its true potential realised.
By the way, didnt that leave a hole in your wall?
What's another hole ;)
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Gippeto
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Sat Jan 03, 2009 3:52 pm

Very nice Jack. :) It's "sleek" looking.

Does your new shock pump open the schrader valve too? Looks as though it might.

Cracking pressure be damned. :D


What's another hole
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jackssmirkingrevenge
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Sat Jan 03, 2009 3:58 pm

Gippeto wrote:Does your new shock pump open the schrader valve too? Looks as though it might.
Yep, that purple anodised bit is a separate threaded bit that presses the stem independently.
Cracking pressure be damned. :D


Actually I modded the shcrader somewhat, if you can call it that. Basically clipped off the the bulged bit that stops the stem from coming out and stretched it a bit, seems to have weakened the spring to the point that there's practically no resistance.
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