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Copper spudgun

Built a pneumatic cannon? Then post it here! This section is for completed, finished cannons that you have built. Please include pictures and information.
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Unread postAuthor: wyz2285 » Mon May 17, 2010 3:17 pm

you need a better barrel,and a scope,it helps a lot.
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Unread postAuthor: Biopyro » Mon May 17, 2010 4:39 pm

Define "better barrel"?
That's not great accuracy at all.
I suspect the high power is causing destabilising muzzle blast, so perhaps consider a muzzle brake or suppressor style holes in the end of the barrel* to vent the fast moving gas after the projectile is moving. This will hopefully prevent the projectile tumbling too much/ being knocked off course.
A longer barrel would help too, but maybe a tank style break would give the same accuracy without the length.


*I'm sad that I don't remember what this is called, it's been too long :(
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Unread postAuthor: Lockednloaded » Mon May 17, 2010 5:59 pm

Biopyro, i think they are called "barrel ports" but not sure. Is muzzle blast interference really a huge issue? at what point does it begin to throw off accuracy?
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Unread postAuthor: Patto » Mon May 17, 2010 9:23 pm

nice build man :D

I'd try changing your projectile ?? maybe steel balls ?
smooth bore @ 100psi you should be able to hit consistently 10 - 15m :lol: mine does well over 12m at least 4/5 keep it up and good luck
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Unread postAuthor: Biopyro » Tue May 18, 2010 2:07 am

Lockednloaded wrote:Biopyro, i think they are called "barrel ports" but not sure. Is muzzle blast interference really a huge issue? at what point does it begin to throw off accuracy?


Yes I think you're right there, thanks.

It's hard to define a point when it happens exactly, but it becomes more likely as the C:B ratio decreases (currently quite low at 0.54) and as the pressure increases (100psi is not unreasonable), so I would put it down to the C:B.
Now I've done the calculation I'm pretty sure that some barrel ports would go a long way here.
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Unread postAuthor: Labtecpower » Tue May 18, 2010 1:58 pm

I added a muzzle brake today. I have the idea that it improved accuracy a small bit.
The only bad thing is that the holes in my muzzle brake is shredding my paper wadding into a sort of confetti cloud :D .
I made some iron sights, this improved accuracy very very much.
Without sights I sometimes missed the back stop ( :shock: ), but now I can hit the back of a tin from 10 meters away.

Edit: typo's :evil:
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