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Simple coaxial shotgun

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Simple coaxial shotgun

Unread postAuthor: Marffy » Wed Nov 28, 2012 11:43 pm

So i finally finished my muzzle loading piston air gun. I've only taken it to 150psi but its got some good power, can't wait to bump up the pressure.

Specs:
Chamber: 2' .75" galvanized steel
Barrel: 36" .5" OD steel tube ~.44 cal
pilot: 1/4" modified blowgun
fill valve: schrader


the piston is a wine cork, with glue on one end, and a bolt thru the whole thing that attaches a neoprene washer as a sealing face. I'll get images up next time i open the gun up.

Image

Image

Overly complicated barrel support:
Image

Image

Image

Image

Image

overall i'm very pleased with how it turned out, i still have to sand the stock some more and rig some iron sights.

I'm also going to test it for leaks underwater but for now it seems to hold air just fine.
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Last edited by Marffy on Wed Nov 28, 2012 11:53 pm, edited 1 time in total.
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Unread postAuthor: Lockednloaded » Wed Nov 28, 2012 11:48 pm

Nice simple gun you've got there, great work with the stock.

Did you roughen up the inside of that hose barb and your barrel? If so it looks like you're ready for some high pressure fun :D
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Unread postAuthor: Marffy » Wed Nov 28, 2012 11:56 pm

Lockednloaded wrote:Nice simple gun you've got there, great work with the stock.

Did you roughen up the inside of that hose barb and your barrel? If so it looks like you're ready for some high pressure fun :D


no, i just left it as i got it. i didn't think of doing so untill after i glued it. one side is filled with hot glue so i think the piece will hold together but it just might leak at high pressure.
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Unread postAuthor: jackssmirkingrevenge » Thu Nov 29, 2012 2:06 am

Looking good, hope your piston can take the strain of higher pressures.
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Unread postAuthor: jrrdw » Thu Nov 29, 2012 6:12 am

jackssmirkingrevenge wrote:Looking good, hope your piston can take the strain of higher pressures.


I was also wondering about that. Cork piston could be a first here...
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Unread postAuthor: Marffy » Thu Nov 29, 2012 8:35 pm

jrrdw wrote:
jackssmirkingrevenge wrote:Looking good, hope your piston can take the strain of higher pressures.


I was also wondering about that. Cork piston could be a first here...


I used to shoot corks out of 3/4" barrels so thats where i got the idea. Its working great so far. It doesn't need a bumper and won't crack in half
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Unread postAuthor: jackssmirkingrevenge » Fri Nov 30, 2012 1:01 am

Do you mean a cork cork or a rubber "cork"?
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Unread postAuthor: Marffy » Sat Dec 01, 2012 1:08 am

jackssmirkingrevenge wrote:Do you mean a cork cork or a rubber "cork"?

wine cork, so.. rubber cork.
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Unread postAuthor: Zeus » Sat Dec 01, 2012 1:55 am

We've been using them for ages, we assumed you meant a cork made from cork.

Down here, I've never seen a rubber wine cork.
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Unread postAuthor: Marffy » Sat Dec 01, 2012 7:12 pm

heres a little update:

barrel in the chamber:
Image

the piston:
Image

it started to leak today so i opened it up to see what was wrong
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Unread postAuthor: drmoreau » Tue Jan 29, 2013 12:57 pm

I'm curious about the firing mechanism. I get how you've got the schrader valve to put pressure into the system, but it looks like your trigger is an air blower attachment for an air compressor system....when you pull the trigger won't all of the air just come out of it where the trigger is though? How is this supposed to release the pressure down the barrel? I'm confused.
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Unread postAuthor: jackssmirkingrevenge » Tue Jan 29, 2013 1:52 pm

drmoreau wrote:I'm confused.


No you're not: http://www.spudfiles.com/forums/piston- ... t8157.html
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Unread postAuthor: drmoreau » Tue Jan 29, 2013 2:02 pm

honestly the diagram in the link seems incredibly complicated for something as simple as releasing pressurized air, lol.

even then, I still don't see a pressure tank on this gun so I don't see where the air is coming from to fire the projectile when the valve is released.
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Unread postAuthor: jackssmirkingrevenge » Tue Jan 29, 2013 2:05 pm

This is basically how it works:

Image

In the case of the subject of this thread, instead of filling and firing with the same tyre valve, he's using the tyre valve for filling and the blowgun valve for firing - but the concept is identical.
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Unread postAuthor: drmoreau » Tue Jan 29, 2013 2:07 pm

neat, but I don't like lots of parts, especially moving ones, lol. i'm a firm believer in KISS (keep it simple stupid), hehe.

thanks for explaining it though.
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