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Barrels

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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Unread postAuthor: MrCrowley » Sun May 13, 2012 12:19 am

To be fair to matty, the entire discussion is solely about air rifle pellets (or at least diameters). It would be pretty hard to miss that if you read the first post.
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Unread postAuthor: Bowman » Sun May 13, 2012 12:25 am

To be honest, I didn't really read the entire first post. I saw the thread was in the pneumatic cannon discussion and not the BB/Pellet gun discussion. And I kind of just posted what I thought would help but apparently not. Will read next time lol :oops:
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Unread postAuthor: wyz2285 » Sun May 13, 2012 5:08 am

Gippeto, here is a basic diagram of what I have in mind
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CpTn_lAw wrote::D "yay, me wanna make big multishot pnoob with 1000 psi foot pump compressor using diamond as main material. Do you think wet bread make good sealant? " :D
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Unread postAuthor: mattyzip77 » Sun May 13, 2012 8:03 am

MrCrowley wrote:To be fair to matty, the entire discussion is solely about air rifle pellets (or at least diameters). It would be pretty hard to miss that if you read the first post.


Thank you, and wasnt being a douche, just read the thread dude!!
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Unread postAuthor: wyz2285 » Sun May 13, 2012 8:59 am

!!

Stop using exclamation mark every time you writes, please :| do you yell every times you open your mouth in real life too?
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CpTn_lAw wrote::D "yay, me wanna make big multishot pnoob with 1000 psi foot pump compressor using diamond as main material. Do you think wet bread make good sealant? " :D
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Unread postAuthor: Gippeto » Sun May 13, 2012 10:07 am

Couple things come to mind about your drawing...

If you keep it like that, you'll not be needing to chamber the barrel...square it off, chamfer @ 60 degrees, polish this bit and yer done. Keep tolerances as close as possible though...or you'll have problems.

An awful lot of dead space though.

You don't want the pellet making a transition from your receiver into the barrel during the shot cycle...make the bolt longer such that it seats the pellet completely into the barrel. Keep in mind that the "pin" probe you've drawn will seat varying pellets to different depths as the hollow section of the skirt varies with weight and manufacturer.

This is "in part" anyway, why I'm liking the flow through bolts...every pellet gets seated to the same depth. The pellets also are encouraged to enter the rifling "square".

Magazines "handle" the pellets...IMO anything that handles the pellets creates opportunities to damage those pellets. For greatest accuracy potential, I would stick with single shot. There certainly are accurate rifles with magazines though....it's up to you. :)

Transfer port should be .100" max for .177. If you build it as drawn, I'll suggest you drill and tap from the side into the transfer port, and install an adjustable restrictor screw. The Air Arms has this and it allows for an easily adjustable power output.

Give some thought as to how you're going to attach the receiver to the main tube and seal the transfer port to the valve as well. With the "saddle" on the underside of the receiver a couple quality #8 screws will be plenty.

Scope attachment also needs to be thought out. Could cut a rail (11mm dovetail or weaver/picatinny...whatever you have room for) or drill and tap for a bolt on weaver rail. Watch the height of the magazine...it might interfere with scope mounting.

Making the receiver a little "taller", gives you the option of adding forward slope to the rail... 1/8"FS over 6" is IIRC something like 27moa..this would pay dividends for scope adjustment if you intended to do any longer range shooting. :wink:

Will let you chew on that for a bit. :)
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Unread postAuthor: dewey-1 » Sun May 13, 2012 10:24 am

wyz2285 wrote:
!!

Stop using exclamation mark every time you writes, please :| do you yell every times you open your mouth in real life too?

wyz;

Be a little considerate here.
Be a little considerate here!
Be a little considerate here.!!
BE A LITTLE CONSIDERATE HERE! (Now that is yelling)
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Unread postAuthor: mattyzip77 » Sun May 13, 2012 11:54 am

SORRY :!: :!: :!: :!: :!: :!: :!: :!: :!: :!:
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Unread postAuthor: wyz2285 » Sun May 13, 2012 1:46 pm

Sorry :oops: but it does makes me feel annoyed :roll:
Gippeto: So I should drill a hole on my 100 euro barrel? :shock:
About the magazine, it´s giving me a lot of work design a proper one for machining, so I´d be more than happy about get rid of it :lol:
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Last edited by wyz2285 on Sun May 13, 2012 2:03 pm, edited 2 times in total.
CpTn_lAw wrote::D "yay, me wanna make big multishot pnoob with 1000 psi foot pump compressor using diamond as main material. Do you think wet bread make good sealant? " :D
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Unread postAuthor: mattyzip77 » Sun May 13, 2012 1:50 pm

Wasnt tryin to annoy you, just how I type, look at any one of my posts and there will be a exclamation point!! Think of it as my sig!!
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Unread postAuthor: Goats spudz » Sun May 13, 2012 5:09 pm

Wyz you want something like this
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look at the transfer block part
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Unread postAuthor: wyz2285 » Sun May 13, 2012 5:41 pm

Then when I fire it the pellet will have to pass through the barrel/tube section, the accuracy probably is ruined. No?
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CpTn_lAw wrote::D "yay, me wanna make big multishot pnoob with 1000 psi foot pump compressor using diamond as main material. Do you think wet bread make good sealant? " :D
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Unread postAuthor: Goats spudz » Sun May 13, 2012 6:14 pm

wyz2285 wrote:Then when I fire it the pellet will have to pass through the barrel/tube section, the accuracy probably is ruined. No?
The pellet probe should push the pellet into the rifled barrel, to reduce deadspace you could make the transfer tube as short as possible :)
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Unread postAuthor: warhead052 » Sun May 13, 2012 7:33 pm

That may not work the way you intend, plus it will be difficult enough to line up the holes. Why not just go ahead and have it built together, like a pellet rifle that you could buy?
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Unread postAuthor: Goats spudz » Sun May 13, 2012 9:24 pm

Why would it be hard to line up the holes, if the transfer part is the same dia and internal dia and the boring is done correctly it should line up perfectly, any good machinist would do it,
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