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Micro BBMG musings

This area is for the discussion of BB or airsoft sub machine guns, and or other small arms such as pellets.
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Unread postAuthor: psycix » Tue Mar 17, 2009 10:48 am

jackssmirkingrevenge wrote: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.

Well, you gotta do it with 12, 88 or a really large one. Make your pick.
If 12 is to small, try to get hold of the 88's (expensive?)
I'm sure you can solve any problem you encounter with your holy essence.

jackssmirkingrevenge wrote:double post, sorry
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jackssmirkingrevenge wrote:triple post, sorry :?
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Unread postAuthor: suture self » Tue Mar 17, 2009 9:58 pm

[quote]does anyone know of an adapter from 12 gram threaded to 88 gram?

wal mart sells the 12g to standard paintball size,maybe 88 fits? i think they (88's) come with an adaptor so there you have it... 8)
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Unread postAuthor: jackssmirkingrevenge » Wed Mar 18, 2009 1:15 am

I would need an adapter that gets the larger 88 gram thread to fit in a female socket made for the 12 gram thread.

In any case, this project is on hold while I build me a tiny hammer valve.
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Unread postAuthor: jook13 » Wed Mar 18, 2009 1:27 am

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Unread postAuthor: THUNDERLORD » Fri Mar 20, 2009 10:22 am

jackssmirkingrevenge wrote:I would need an adapter that gets the larger 88 gram thread to fit in a female socket made for the 12 gram thread.

In any case, this project is on hold while I build me a tiny hammer valve.


The 88 gram, 2 pack of carts I see in WalMart lately come with an (one) adapter for use in larger Paintball threads.
Looks like a large pin valve where it could be unthreaded and still hold it's CO2.
And probably not designed for it but somehow refilled(?)
Unfortunately, I'm not very familiar with PB stuff. (Soon though hopefully).

I think "Judgement_Arms" mentioned he works around a PB shop(?)
Maybe we could summon "The Judge" somehow(?)

Course with the CO2 dummy 12 gram (Available at palmer's and elsewhere), Perhaps all you'd need is the hose running between, and to mod the filler handle by drilling a hole in it...

BTW, With the hammer valve it sort of amazes me the 40-60 KA-POPs that come from a most CO2 pistols with hammer valves, while the tire fillers dump the co2s at a HISS for 3-4 sec.s...I was wondering about a burst fire (hammer mechanism) that would work similar to your piston valve burst chamber myself. 8)

OH, I made a misprint earlier, I wrote "RPS" and meant "RPM" :oops: 8)

EDIT: If your filler only accepts threaded Cart.s , a handle could be constructed with a nut (perhaps the type shaped like a top hat you see on wire spools in plywood) on the inside bottom of handle.
Then a bolt could be threaded through to press the non-threaded co2(or dummy cart.) against the valve...
A mod I was thinking of for mine because the handle takes up space.
(I was thinking of an adaptable mauser broomhandle shape for a while myself is all) :)
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Unread postAuthor: jackssmirkingrevenge » Fri Mar 20, 2009 12:04 pm

Making a micro hammer valve as we speak, expect a build log of sorts soon ;)
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Unread postAuthor: THUNDERLORD » Sun Mar 22, 2009 1:48 am

Nice working Hammer valve JSR!
My tyre filler takes 16 gram cart.s also.
They look a little strange because bigger diameter and longer.
the extra 4 grams was barely noticeable time wise though.

Off topic slightly but besides tire fillers, I've noticed co2 12 or 8 gram drain clog clearers (plumbing shop) and also Cabelas(?) or somewhere have a co2 12 gram for clearing jammed bullets in muzzle-loaders (screws into the nipple hole when the nipple is removed).
Neither is more useful though because the other two compact co2 dispensers have no shrader threads.

Still off topic slightly but for automotive use I'm wondering about a homemade n20 (NOS) kit by using the dummy co2, tyre filler, hose, and remote n2o tank storage, with a hose to carburator (more compact for MC use :) )...wonder what type valve the normal automotive nitrous kit has(?) probably electric solenoid, but rated for high pressure n2o(?)

I noticed suture self already had replied before me on the last reply.

I've got a dry-ice local supplier. Wonder of the 88 gram had chopped up pieces funneled in and the Paint ball adapter threaded back on, what type volume could be obtained safely.
I'd need more info before trying that because rupture at close range would most definately cause dismemberment or death... :evil: 8) 8) 8)
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Unread postAuthor: suture self » Sun Mar 22, 2009 10:00 am

NOS i'm assuming wouldn't be cost effective,... but dry ice, wow now we're getting somewhere. is that stuff cheap? someone should try it :twisted: let us know if your still alive afterwards...
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Unread postAuthor: jackssmirkingrevenge » Sun Mar 22, 2009 1:36 pm

Interesting thoughts, but I think I'd rather work with HPA. I had freezing problems with the 12 gram through the hammer valve.
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Unread postAuthor: THUNDERLORD » Fri Mar 27, 2009 12:58 pm

suture self wrote:NOS i'm assuming wouldn't be cost effective,... but dry ice, wow now we're getting somewhere. is that stuff cheap? someone should try it :twisted: let us know if your still alive afterwards...


I found it in a normal grocery store nearby for 1$ a pound.
Not sure yet what volume that will yield...Plan to find out soon. :D

It's used often for catering food.
Or putting in plant chambers or bags around home plants or gardens, since plants breathe CO2 in daytime, they will grow bigger/faster.
Like I stated, the pressures it generates (when contained) are very dangerous. :twisted:

As for the N2O, the whip cream 8 gram CO2 size, would be useful for certain mini or micro hybrids IMO, because the high pressure and small package.

Although I've seen oxygen alone in 4500psi tanks for welding and it's supposedly a better oxidiser. (Brass pipe nipples between reg and tank too.)
BTW, There was a post somewhere on SF's about using a constant spark gap, constant fill propane, Then adding 300 something psi air and it would not fire until that point...pretty cool concept for a hybrid IMO.
With the co2 filler I was just stating N2O instead can be used is all.
Enough ranting, I got no time till later... :( 8)
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Unread postAuthor: Ragnarok » Fri Mar 27, 2009 1:48 pm

To point it out, it's not appropriate to call the gas NOS. It's Nitrous Oxide or N<sub>2</sub>O - NOS (Nitrous Oxide Systems) is merely a company that sells systems that use the gas for enhancing car performance.

It is not a name for the gas itself.

THUNDERLORD wrote:I found it in a normal grocery store nearby for 1$ a pound. Not sure yet what volume that will yield...Plan to find out soon.

By my reckoning ~8.5 standard cubic feet (that is, at atmospheric pressure).

Although I've seen oxygen alone in 4500psi tanks for welding and it's supposedly a better oxidiser.

Depends. For the same molar quantity of it, you can oxidise twice as much fuel with oxygen.
However, N<sub>2</sub>O does have a positive molar enthalpy change of formation.

What this means is that for a fixed amount of oxidiser, oxygen is better. For a fixed amount of fuel, Nitrous Oxide will generate slightly more energy output - however, at a loss of end temperature and thus speed of sound in the combusted mixture.

EDIT: Just to point it out, the reason Nitrous oxide is used as an oxidiser is because it can be compressed to a liquid, which makes it easier and cheaper to store.
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Unread postAuthor: Lentamentalisk » Sat Mar 28, 2009 12:46 am

Well in that case it is clear that we need to make a N2O(l)/Propane(l) hybrid... Now that would be something...

Would that even work, mixing a liquid oxidizer and a liquid fuel, and then igniting?

edit: fixed
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Unread postAuthor: Ragnarok » Sat Mar 28, 2009 2:21 am

Lentamentalisk wrote:Would that even work, mixing a liquid oxidizer and a liquid fuel, and then igniting?

That might be getting on the side of against forum rules.
Although Rule 3 specifically says "no solid propellants", I think it's interpretation is closer to "Gaseous oxidisers only".

However, to make a brief note on a theory viewpoint only...

Yes, it would presumably work. Igniting it might either prove pretty hard, or it might prove very sensitive.
The pressures that would be generated would obviously be pretty damn high - but you'd lose some energy in converting the liquid propellants to the post combustion gas.
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Unread postAuthor: psycix » Sat Mar 28, 2009 3:36 pm

It would be very dangerous, thats for sure.
I think that DDT becomes almost inevitable.
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Unread postAuthor: jackssmirkingrevenge » Tue May 12, 2009 9:33 pm

Update on this idea, I'm making a variation to be used with my paintball tank. Basically a small BB chamber (about 120 3mm BBs capacity) connected on one end to a heavily chopped blowgun and on the other a 15 inch 3mm barrel with a sprung detent to limit firing pressure tp the 500-800 psi range. Here's the core of the setup before I bury it in an epoxy casting:
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