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Posted: Mon Mar 16, 2009 2:35 pm
by jackssmirkingrevenge
psycix wrote:I think the coaxial idea is worth trying. You are looking for compactness, and thus coaxial is the way to go.
This is what I had in mind, using a relatively tiny BB chamber good enough for less than 3 seconds worth of firing in order to maximise performance by reducing the expansion volume before firing. This is with 12 grams in mind, if I find a bigger gas source I'll make a bigger BB chamber.

Posted: Mon Mar 16, 2009 2:41 pm
by jook13
Look into those 88 gram crossmans?

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Posted: Mon Mar 16, 2009 2:43 pm
by ALIHISGREAT
it will work... but will it be any good? now that'd debatable!

I would however like to see it done, but maybe a bigger air source will be more fun?


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a 4oz CO2 tank would be better, i'm not sure of the threads though?

Posted: Mon Mar 16, 2009 2:54 pm
by jackssmirkingrevenge
jook13 wrote:Look into those 88 gram crossmans?
That would be an easy solution but I'm sure the threads don't fit the inflator as they're wider, does anyone know of an adapter from 12 gram threaded to 88 gram?

A cheaper idea in the long run would be one ofthese refilled from my SCUBA.

as a sidenote, basing the casing on a machine pistol like the Tuma MTE would make for an even more compact package :twisted:

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Posted: Mon Mar 16, 2009 3:16 pm
by ALIHISGREAT
A cheaper idea in the long run would be one of these refilled from my SCUBA.
I wish i had a SCUBA tank... imagine the guns i could use with that :shock: i do have a 1.1L 4500psi paintball tank so its not all bad :D

i'll have to make a BBMG out of that at some point, its regged down to 800psi so i would be ideal for a project like this except for the size obviously.

Posted: Mon Mar 16, 2009 5:58 pm
by jackssmirkingrevenge
ALIHISGREAT wrote:i do have a 1.1L 4500psi paintball tank so its not all bad :D

i'll have to make a BBMG out of that at some point, its regged down to 800psi so i would be ideal for a project like this except for the size obviously.
About these tanks - where's the valve :?

Posted: Mon Mar 16, 2009 6:14 pm
by jook13
Make your own, epoxy boy!

Posted: Mon Mar 16, 2009 6:20 pm
by jackssmirkingrevenge
Seriously, I've never actually handled one of these. Does a valve open when you screw it in? I'm guessing the bottle can be filled when it's not attached to the marker.

Posted: Mon Mar 16, 2009 8:36 pm
by Leonard
HPA tanks have the same valve as a c02 paintball bottle. Pin valve and ASA threads. Pin valve open when tank is screwed in.

By the way, the 88 grams c02 canister need an adapter to be converted to ASA regular paintball threads. Then you would need an ASA adapter to 1/8" npt (like the one sold on palmer's pursuit shop) That's a lot of adapters.

Posted: Mon Mar 16, 2009 8:57 pm
by pharmboy
Also, the 88 gram CO2 cylinders have a puncture disk sealing the opening. When you screw it into the ASA adapter, it's just like a really big 12 gram being loaded into an air pistol. The ASA adapter has a pin valve just like the larger CO2 tanks.

Posted: Tue Mar 17, 2009 1:25 am
by jackssmirkingrevenge
Thanks for that guys. I might be going in a different hammery-valvey sort of direction with these micro calibre thoughts though as indicated here...

Posted: Tue Mar 17, 2009 2:41 am
by ALIHISGREAT
jackssmirkingrevenge wrote:Seriously, I've never actually handled one of these. Does a valve open when you screw it in? I'm guessing the bottle can be filled when it's not attached to the marker.
As has already been mentioned, the Tanks have a pin valve but unlike CO2 (which are filled through the top) HPA tanks are filled from a fill nipple on the side of the tank (do not even think about putting any lube or oil anywhere near the fill nipple)

The easiest way i see of attaching the tank is to buy an On/off ASA (where the pin that opens the tank moves backward to turn the air off) the ASAs have a 1/4" NPT thread coming out so it would be quite easy so attach it directly to a project with off the shelf parts.

Or Alternatively, you could use a remote line...

Posted: Tue Mar 17, 2009 3:05 am
by jackssmirkingrevenge
Thanks for that.
ALIHISGREAT wrote:Alternatively, you could use a remote line...
I'd rather have it as one unit. The HPA tanks seem more convenient too as the fill nipple probably fits nicely into the adapters I use to fill my air rifles.

Posted: Tue Mar 17, 2009 3:05 am
by jackssmirkingrevenge
double post, sorry

Posted: Tue Mar 17, 2009 3:05 am
by jackssmirkingrevenge
triple post, sorry :?