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Unread postPosted: Thu Apr 12, 2007 4:14 pm
Author: paaiyan
8 mm for bb's? Seems a bit excessive. Unless you're going for an airsoft shotgun.

Unread postPosted: Thu Apr 12, 2007 4:25 pm
Author: jackssmirkingrevenge
paaiyan wrote:8 mm for bb's? Seems a bit excessive. Unless you're going for an airsoft shotgun.


That will allow the BBs to flow freely while still allowing enough air to blow past them to propell the BBs in front of them, removing the need for any holes along the magazine that would only interfere with the airflow.

Unread postPosted: Thu Apr 12, 2007 4:43 pm
Author: paaiyan
Well, I don't know what kind of bb's you're using, but mine are about .5 mm. 8 mm tube would be really excessive.

Unread postPosted: Thu Apr 12, 2007 4:55 pm
Author: jackssmirkingrevenge
I think your BBs are 4.4mm, not .5 :p

I was assuming this was for 6mm airsoft BBs. For 0.177 BBs a 6mm magazine tube will suffice.

Unread postPosted: Thu Apr 12, 2007 5:16 pm
Author: paaiyan
Gah, forgot to convert from cm to mm. Now I feel intelligent. Yea my first thought when I hear bb is .177 cal. That's what my air rifle takes.

Unread postPosted: Fri Apr 13, 2007 3:01 am
Author: Redcoat
im doing something like this with my bb gun im making for the competition i hope it works

Unread postPosted: Fri Apr 13, 2007 7:56 am
Author: FeLeX
Well first of all thank you very much for the picture! Now I get it. Thats actualy pretty good idea. Back when I used to live in York (England) me and my parentals went to Black Pool, they had this attraction there (sorryz I dont know what American call it I am from Russia) You pay a pund and you get 100 bbs, they put them into this gun. They load them from the back and the gun was connected to the air compressor. I could never seem to figure out how it works, aparently its based on the Vogt cycle! Anyways you get 100 bbs and if you manage to destroy this paper circle you get 10 punds back. Pretty cool thing, the only thing is I never won. =(
I might have to try this, looks pretty cool. Good luck with it mate and I cant wait to see your pictures of it!

Unread postPosted: Fri Apr 13, 2007 8:52 am
Author: Solo
Ok, you guys aren't getting it. I based the whole thing off this gun:
http://www.spudfiles.com/forums/bv150gbmg-t6826.html

The principle is that the air comes into the barrel/mag through that hole(s) which is smaller in diameter than your bb so it doesn't fall out. The bb's get sucked out of the mag end of the barrel, past the hole, and then blown out the barrel.

Correct me if I'm wrong, but I think Jack here has made a strafer that involved a ball valve somewhere on the barrel, think this was the topic but the pictures don't work for me so I can't really tell:
http://www.spudfiles.com/spudtech_archi ... php?t=8712

Unread postPosted: Fri Apr 13, 2007 9:08 am
Author: jackssmirkingrevenge
The spudtech link above refers to the prototype illustrated in this thread. Why do you need the BBs to get sucked out as well as blown out? The hole will allow air to blow out of the barrel without taking the BBs with it, as well as creating turbulence that will reduce the power of the system.

I think your best bet is to have air flowing in the magazine tube through one end, that way all the BBs will be forced out without excess air being wasted.

Unread postPosted: Fri Apr 13, 2007 9:48 am
Author: paaiyan
I agree with Jack, that hole toward the front won't help in any way and will probably just cause it to lose power.

Unread postPosted: Fri Apr 13, 2007 1:06 pm
Author: Solo
thanks for the link Jack, I knew I'd seen it somewhere on here but I couldn't find it.

*sigh* The point of having the bb's sucked forward is that I'm not going to let air into the rear of the barrel: I tried to show it in the diagram, that end is plugged. The only air coming into the barrel is thru that hole in the side. According to the theory (which is not mine, I guess it's DR's) this should automatically pull only one bb at a time past the hole, so you don't get more than one in the barrel at once. I don't know how fast it loads a new bb after the last one leaves the muzzle, but I was hoping it would be quick enough to where you wouldn't loose too much air between bb's.

here's what DR said:

As the air is dumped out of the valve, it passes through a 1" hole that is drilled through the 1-1/2" sdr21 sleeved barrel. The airflow sucks a ball out of the magazine and past the 1" opening.

After it passes the 1" port, pressurized air forces it down the barrel!
Each successive ball is pulled and pushed in the same fashion, until there are no balls left. This all happens very quickly, hence the full-auto designation.


I don't know how air-efficient that is, but 10 rounds per second for a golf ball on that barrel sounds pretty good to me. I imagine it would cycle a heckuvalot quicker with bb's.

Unread postPosted: Fri Apr 13, 2007 2:18 pm
Author: FeLeX
jackssmirkingrevenge wrote:The spudtech link above refers to the prototype illustrated in this thread. Why do you need the BBs to get sucked out as well as blown out? The hole will allow air to blow out of the barrel without taking the BBs with it, as well as creating turbulence that will reduce the power of the system.

I think your best bet is to have air flowing in the magazine tube through one end, that way all the BBs will be forced out without excess air being wasted.


If the air would just blow through the hole without grabbing any bbs how did DRs cannon work then?

Unread postPosted: Fri Apr 13, 2007 6:55 pm
Author: TwitchTheAussie
Why dont you incorporate a vortex block? Instructions here
http://www.burntlatke.com/bb.html
It would get some more efficiency out of it.