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Micro BBMG musings

Posted: Sun Mar 15, 2009 12:20 pm
by jackssmirkingrevenge
This is an idea that has been fermenting in my head for at least 4 years, if this post on spudtech I dug up is anything to go by:
What I was thinking was a 3mm calibre device using lead shot of the appropriate size as ammunition in a scaled down vortex block. Combined with a 12 gram CO2 powerlet you'd get (as far as my theory goes) a few seconds - several hundred shots - worth of firing time in a very compact package.
Now, finally, I should shortly be receiving a supply of 3mm (0.118") BBs in large enough quantities to be used in a BBMG. Basically the plan is to take a CO<sub>2</sub> tyre filler and hook it up to a cloud chamber, it should be vaguely similar to Brian's PNUZI but since it has a smaller outlet, the gas supply should last longer - and of course, I'd have no problem with making provision for a longer barrel :P

I was tempted to go even smaller and use 1mm (0.039") BBs as ammunition but I'm pretty sure that at that size, I would have more of a sandblaster than a machinegun :roll: so 3mm is about as small as you can practically go.

I would also like to try out a burst fire pen gun, something conceptually similar to this design but co-axial so the chamber has to be wider than 6mm to accomodate the BB reservoir, marker gun perhaps.

As always, watch this space :)

edit: here's how it's looking in my head:

Image

Posted: Sun Mar 15, 2009 1:54 pm
by Carlman
ive actually allready done this... :D

i used the ammo from my 3mm bb blow gun..gun.

using 40mm poly pipe nipple around 50mm long with endcaps and using 160psi shop compressor and a carbon fibre 1m long barrel.

got bloody good performance ripped the shiza out of cans and so on. ammo was expensive at those quantities so i dismantled it.

Posted: Sun Mar 15, 2009 2:33 pm
by THUNDERLORD
I'll keep watching this space then ! 8)

Had a similar idea of just removing the internal pin in a tire shraeder valve, attaching it in a copper end-cap ...I was wondering if plumbing copper could handle a jam though(?)

I get only about 3-4 seconds from a 12 gram cart. in my filler.
But (for authenticity) at 600 RPS and a 30 round mag, a real SMG is about the same time , course on the SMG it's less of a pain than installing a new co2 each 3-4 seconds.
Sounds like your 3MM BB's will be more fun to shoot!

A dummy co2 , PB hose and larger tank would be a nice accessory for that still IMO.

It's cool to know what you're working on JSR! :wink: 8)

Posted: Sun Mar 15, 2009 3:13 pm
by Brian the brain
I hate you...no I don't :D

Can't wait!

If it's worthwile, I might convert the Pnuzi.

Posted: Sun Mar 15, 2009 7:08 pm
by jackssmirkingrevenge
Carlman wrote:ive actually allready done this... :D
awwww, why haven't we seen it then?

Thing with smaller calibres, as one sees from penguns, is that moar pressure is a significant requirement.
I get only about 3-4 seconds from a 12 gram cart. in my filler.
But (for authenticity) at 600 RPS and a 30 round mag, a real SMG is about the same time , course on the SMG it's less of a pain than installing a new co2 each 3-4 seconds.
Indeed, some smaller machine pistols can empty their magazine in less than 2 seconds. I have to see if I can find 88 gram CO<sub>2</sub> cartridges, that or have a tank strong enough to be refilled from my SCUBA :)

Posted: Sun Mar 15, 2009 7:32 pm
by inonickname
Go ahead and use the CO2 bulbs, but you could drill a hole in the bottom, tap a 1/8 or 1/4" thread and screw in a QD(checked)/schrader. Then use a fridge compressor if you wanted to save money and have semi portable carts.

Should be good, and you can literally make a sandblaster if you go small enough (with a fair amount of pressure).

Lets see another monster from JSR then.. :P

Posted: Sun Mar 15, 2009 7:52 pm
by jackssmirkingrevenge
Maybe I should just fork out for something like this and have a proper little power house :twisted:

Posted: Sun Mar 15, 2009 8:25 pm
by inonickname
I think a supersonic strafer would be suitably impressive. Wouldn't be very cheap though..

Posted: Sun Mar 15, 2009 8:54 pm
by pharmboy
Well, as far as smallbore ammo, have you guys looked into steel shot for reloading shotgun shells? looks like it runs about $25/10 lbs. Not exactly cheap, but you can get probably 10,000 shots out of a 10 lb supply of it.

http://www.outdoorsmansupply.com/store/243_1163.asp

Posted: Sun Mar 15, 2009 10:34 pm
by Carlman
i was in my 'cbf posting anything' time :D

in that time I also made a small coax, propane powered pnue piston grape gun and a spray and pray lol.

Posted: Mon Mar 16, 2009 1:36 am
by jackssmirkingrevenge
pharmboy wrote:Not exactly cheap, but you can get probably 10,000 shots out of a 10 lb supply of it.
More like 7,500, about 1 cent for every 3 BBs - not so bad, plus they're steel so a quick cruise of your shooting range with a magnet and you can reuse them.
inonickname wrote:I think a supersonic strafer would be suitably impressive. Wouldn't be very cheap though..
It need not be too expensive either. You can get a reasonably sized HPA tank and a pressure washer handle for less than $100, barrel and BB chamber wouldn't add more than $20 and that would enable you to use unregulated HPA at up to 4,500 psi - I'm cutting out the cost of a SCUBA tank which I already own - which would be scary to say the least. What puts me off is the fact that at those pressures, putting any epoxy into the equation would be risky so it would have to be standard fittings all the way - something which I'm warming up to, but not quite there yet.
Carlman wrote:i was in my 'cbf posting anything' time


Actually, now that you mention it, I remember we had discussed the ideabut I don't recall you posting that you had actually made it.

Posted: Mon Mar 16, 2009 7:06 am
by POLAND_SPUD
souns like an interesting idea... but I suppose it's going to be terribly weak due to small diameter of ammo

Posted: Mon Mar 16, 2009 8:24 am
by jackssmirkingrevenge
POLAND_SPUD wrote:but I suppose it's going to be terribly weak due to small diameter of ammo
At longer ranges yes, the BBs will lose power very quickly, but I only need it for close range. With high pressure, it should give pretty high velocity out to a few metres away from the muzzle, and the hardness of the ammunition as well as small diameter should be an advantage in terms of penetration (smaller area therefore greater force exerted on the target).
Brian wrote:I hate you...no I don't


I hope not, 'cause I'll be needing your advice with this whole standard fittings and pressure washer hookup malarkey, all chinese to me :roll:

Posted: Mon Mar 16, 2009 10:35 am
by Carlman
wow i totally forgot i posted that :lol:

ill see if i can dig up some pics buti fear i dumped them with my p4

Posted: Mon Mar 16, 2009 1:31 pm
by psycix
Sounds like fun.
I think the coaxial idea is worth trying. You are looking for compactness, and thus coaxial is the way to go.
BTB wrote:If it's worthwile, I might convert the Pnuzi.
What, unsaw-off the barrel?