Micro BBMG musings

[Technician1002]

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

Yes it would, but plan on being in another state when it goes boom.

Charcoal, oil, paper, and other items are very explosive in liquid oxygen.

In science class we used LOX to freeze things such as roses, balloons, a hot dog, etc. A test on a small piece of paper did not make it brittle, but hitting it with a hammer on the counter made it go off like a 22 shell It got our attention! Anything larger than a small square of paper is getting into the realm of a true Darwin Award. Please don't consider this.

[psycix]

Looks good JSR. What muzzle velocities do you expect / hope for?

[jackssmirkingrevenge]

What muzzle velocities do you expect / hope for?

GGDT suggests somewhere in the region of 900 fps with 450 psi and a 15 inch barrel, of course the BBs weigh next to nothing so it's not much in terms of ft/lbs but penetration should be impressive - plus I have the option to almost double that pressure if needs be I doubt I'll be able to actually measure velocity though as the BBs are too small for the chrony to detect.

A shot at 400 psi from my long pen gun which has a similar barrel length went through both sides of a soup tin and carried on to leave a neat hole through my 6mm thick window

I think rate of fire would still be high though, technically with a lower flow you can regulate the time it takes before a BB "pops" through the detent, but in this case the chamber is tiny and low enough flow won't be enough to agitate the BBs.

Still, can't wait to test it, the epoxy sarcophagus needs to set properly first so the customary 24 hours need to pass, as always watch this space.

[POLAND_SPUD]

would it be possible to achieve ROF of 10 RPS or less??

I think that this has the potential to be something better than your fullauto popoff valve as it's very simple.. I'd love to see it firing 6mm lead BBs

[jackssmirkingrevenge]

would it be possible to achieve ROF of 10 RPS or less??

In this case, I doubt it - as I mentioned, since it's essentially a vortex/cloud type mag it will need good flow to agitate the BBs and so it can't be set too low.

I think that this has the potential to be something better than your fullauto popoff valve as it's very simple.. I'd love to see it firing 6mm lead BBs

I agree - here, no air energy is wasted actuating a piston not would there be any porting restrictions. If you had a spring driven magazine, there would be no minimum airflow requirement so you could set it as low as you want (with the premise of an airtight seal though, either using some rubber tubing before the detent or say the skirt of a pellet sealing against a tight barrel) and you'd effectively have something like the Rattlesnake but where in effect, the projectile itself is the pop-off piston. Again the lack of reciprocation in the design means that there is no minimum airflow so ROF can be as low as you want.

I'm certainly interested in making this in a larger calibre, most probably 0.22". Back to the subject of this thread, in case anyone was wondering what the mould looks like before I pile on the epoxy:

[Ragnarok]

I have a question. How exactly is it reloaded?

[Carlman]

I have a question. How exactly is it reloaded?

I put m vote down for undo the detent and pour them down the barrel, well either that or JSR is gonna reply with a Doh'

[jackssmirkingrevenge]

I put my vote down for undo the detent and pour them down the barrel

That's the idea, I do sometimes make basic oversights but in this case it was planned.

[Ragnarok]

Ah ha, a planned oversight!

A workable plan, but it's going to get tedious fast. Personally, I would be tapping some kind of thread into the side of the vortex chamber that I could plug with a cut down bolt, but... well, I suppose this is standard Jack for you. Can't have threads on it, can you?

[jackssmirkingrevenge]

Can't have threads on it, can you?

That's not true, if I were more "street" I would say it was threadalicious! There's the detent screw, the threaded blowgun valve stem, the bit that screws into the ASA adapter that in turn screws into the paintball tank...

I agree that a separate loading port would have been comfortable, but I don't plan on using this too regularly (3mm hardened chrome steel bearings being at a bit of a premium) so I can live with loading through the barrel. Besides, we're talking less than 150 BBs here.

In any case, too late now... the epoxy filler I'm using is quite interesting, it's an aggregate used in epoxy flooring which I "obtained" - tough stuff and saves you a lot of epoxy

[Carlman]

it looks like you glued a couple of pipe fittings to a chunk of your kitchen bench lol

[jackssmirkingrevenge]

haha true

wanker...

Time will tell if you're either very right or, hopefully, very wrong

update: bugger, it seems that I chopped the blowgun a bit too close, it's not sealing properly now. Ah well, plan B. I hacked off the BB chamber (going through 3 hacksaw blades in the process, damn tough filler) and epoxied a 1/8" male fitting so I can connect it to an unmodded blowgun, which in turn has a 1/8" male fitting on it so I can connect it to the paintball tank ASA adapter. Did someone say not enough threads

Testing due Wednesday though, I'm off for a brief vacation soon

[JDP12]

looks good... quick question...

What's the size of the chamber? What diameter pipe? I'm assuming its only like .5-.34" wide? (as in looking at it from the back, its width, not the pipe diameter)

[jackssmirkingrevenge]

What's the size of the chamber?

The chamber is half an inch of 3/4" pipe, enough for about 120 BBs. I think this would be an interesting direction to take with your handgun ambitions

Here's what it looks like now, I gave it a quick whirl and the power certainly seems to be there, but certainly not a low rate of fire - as I mentioned, while the detent works chamber size is an issue.

I'll do some proper testing tomorrow after work, I think you can expect some impressive damage videos

[JDP12]

hmm... so the pipe essentially is a vortex... not bad..

this could be worthy of looking into.

What pressure were you running at?

I have that exact same blowgun and tried running it at unregged CO2 and it leaked...

any tips??