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Multiple barrel's BBmg

Posted: Thu Nov 13, 2008 5:56 pm
by Demon
No, i did not maked one but...

After thinking that i had never heard of it(seem after making some research)
I tough then i could bring this idea to spudfiles.

Why not put 2 or 3 barrels on a bbmg?

I know that you will need a very big air supply but there will be some really ***** rate of fire! :twisted: ! (maybe 20 000 rounds per minutes with 3 barrels?)

If this is not a new idea, dont post and wait until a mod delete my topic...

Re: Multiple barrel's BBmg

Posted: Thu Nov 13, 2008 6:13 pm
by Ragnarok
Mainly airflow requirements. 100 BBs a second is enough. No-one wants to spend the extra air to fire 200.
Let's be frank, a BB gun that you can only fire for half the time of a simpler variant that does the job well enough isn't worth it. Many people only run their BBMGs at 50 BBs a second for this very reason.

However, there are ways to solve the problems at the same time.
I've got a BBMG design from a few years back that would give ROF a big boost, and at the same time reduce air use by modifying current designs, but like all my other ideas, I don't have the time, money or space to build them.

It's more complex than normal of course, but I think the added difficulty could be well worth it, although I'll be unlikely to get the chance to find out.

Posted: Thu Nov 13, 2008 6:15 pm
by jackssmirkingrevenge
Yes it's been done before, back in the spudtech days. Completely pointless, BBMGs already have too high a rate of fire with one barrel anyway, why would you want to make it worse?

What I want to see is lower rate of fire but greater muzzle energy per shot ;)

Posted: Thu Nov 13, 2008 6:24 pm
by Ragnarok
@JSR: You'd love my hybrid BBMG design. If it ever comes into existence, I'm predicting ~25 rps and somewhere in the region of 10 to 12 ft-lbs per shot.

Posted: Thu Nov 13, 2008 6:27 pm
by jackssmirkingrevenge
Ragnarok wrote:If it ever comes into existence, I'm predicting ~25 rps and somewhere in the region of 10 to 12 ft-lbs per shot.
Still too many rounds per second, I'm thinking of something like the Caselman - in practice something like that using proven valve technology would be a lot more feasible running on air alone that all the systems necessary to make a hybrid function well.

Posted: Thu Nov 13, 2008 6:41 pm
by Ragnarok
jackssmirkingrevenge wrote:Still too many rounds per second
It'll be adjustable, but 25 rps is the limit. You could go pure semi if you wanted, as it loads each shot separately, and triggers each shot independently. With changes to the loader, you could fire airgun pellets or... well, anything basically.

The fact it'd fire 0.2g BBs is because they're cheap (and after any project that would cost as much as this one would, you'd want cheap) and the hybrid part is just because I can. The design would work fine on plain air with a twist or two, although controlling the ROF would then be much harder.

Made out of the right materials, with the right ammo and a longer (and perhaps wider) bore... you could up the pressure quite a lot with the material change, and perhaps get 100 ft-lbs a shot out of it, but that's not what I go for in my designs.

Posted: Thu Nov 13, 2008 7:08 pm
by kablooie
Is there any reason why an o-ring or rubber tube breech wouldn't work to slow the rate of fire and increase the power? I've made a bbmg with a tube breech that runs on very little air (compared to a normal bbmg) at 100 psi, and it will shoot about 2 rounds per second at it's slowest. Even shooting that slowly, the power is very good, although not as powerful as say a semi auto bb gun. Also, I use metal bbs so using airsoft bbs might not work as well (are they rougher?).

Posted: Thu Nov 13, 2008 7:16 pm
by jackssmirkingrevenge
kablooie wrote:Is there any reason why an o-ring or rubber tube breech wouldn't work to slow the rate of fire and increase the power?
Personally I want to try outthis idea, what puts me off is that it only works for spherical projectiles. I'd much rather up the calibre and shoot at least 0.22 airgun pellets.

Posted: Thu Nov 13, 2008 7:38 pm
by kablooie
Hmmm, I hadn't thought about that. Shooting larger pellets would be cool, but wouldn't that mean scrapping the bbmg concept and using a valve? I don't wanna hijack Demon's thread though, so maybe discussion of this should occur elsewhere (or it seems to already have happened).

On the original topic, I agree with everyone else on it not being practical, but I think if some kind of turret or mounted gun was made with a two barreled o-ring breech bbmg, it would be awesome.

Posted: Fri Nov 14, 2008 1:16 am
by jackssmirkingrevenge
kablooie wrote:On the original topic, I agree with everyone else on it not being practical, but I think if some kind of turret or mounted gun was made with a two barreled o-ring breech bbmg, it would be awesome.
What would be "awesomer" is a single barrel opening, but gatling style rotating barrels - that would give you an adjustable rate of fire ;)

Posted: Fri Nov 14, 2008 12:51 pm
by jimmy101
The o-ring type mod does work. I did it a bit differently, but the same basic idea, using a cloud chamber and 0.177 BBs. Instead of an O-ring just cut the barrel near the breach and insert a short length of rubber hose. Tygon works well since it is clear. The ID of the hose needs to be a bit less than your ammo.

During the firing cycle, the high flow through the cloud "chambers" a BB into the tube. The flow drops to zero becuase the tube is plugged and the cloud stops trying to chamber a BB. Pressure builds in the chamber until it is high enough to make the tubing expand. The expanding tubing releases the BB with a heck of a lot more pressure behind it than in a standard cloud or vortex design. (Which only have effective pressures of 20 PSI or so even with a compressor running as 120 PSI.) The high flow through the barrel starts the cloud operating again and the next round "chambers".

Extemely simple. Works pretty well. Trivially easy to replace the tubing when it starts to wear. Much more powerful than cloud/vortex BBMG designs. Much lower ROF. Inconsitent ROF (but clouds/vortexs have the same problem). Probably need to do a study of various types of hose to find the best type.

Always wondered if the rubber hose could in encased in a T. The third inlet to the T could be pressurized (or evactuated) to control the amount of pressure needed to get tubing to expand.

Posted: Fri Nov 14, 2008 2:17 pm
by Brian the brain
You guys aren't ready to embrace the snapvalve/qev set up are you?


Maybe I should up it to .50 one of these days and see if that 'll do it..


Now I only need the cash to do so...

Posted: Fri Nov 14, 2008 2:42 pm
by jackssmirkingrevenge
Brian the brain wrote:You guys aren't ready to embrace the snapvalve/qev set up are you?
I got it to work to some extent, but it's too "obvious" a solution, the human spirit demands that there *must* be another way :D

Posted: Fri Nov 14, 2008 3:20 pm
by Davidvaini
What about a large co2 tank unregulated into a 7 way manifold... then have 7 seperate lines to 7 separate vortex blocks and chambers (7 barrels).

Now I realize the CFM would probably be low per line and I know that you wouldnt get that long of a firing time (unregulated), But I wonder what the ROF would be?

30,000-48300 if all 7 lines had a high enough pressure/volume.

Posted: Fri Nov 14, 2008 3:31 pm
by jackssmirkingrevenge
Davidvaini wrote:30,000-48300 if all 7 lines had a high enough pressure/volume.
You might as well load your wallet into a spudgun and shoot it out of sight :roll: leave the 1,000,000 rounds per minute + stuff to these guys ;)