SpudFiles

I'm in the making of a paintball/airsoft bazooka. the gun uses a ball valve and as we all know ball valves are no good unless you have a HUGE chamber size. Since it has a ball valve i'll be using a union and burst-disk setup after the valve. I'm wondering where the union for the gun should be. Should it be before the ammo or after the ammo? I know for paintballs that the union has to be after the union. But, some airsoft nades (davidvani) have the bbs behind the burst disk. I just want to know what will get me a better performance.

the union has to be after the union.

I'm not sure I follow.

I would say bbs in front of union. That way your wadding doesn't have to go through the (normally reduced inside of the) union. Although you could just dremel it out... It could still have issues...

I don't think either way would have any noticable increase in power. The only power gain you would have if bbs were behind burst disk would be the 2-3 more inches of barrel.

I think david's are behind the disk because most of the time he doesn't use any other barrel except for what is behind the disk.

It goes chamber, connection from chamber to union, union, threaded barrel, and then the bb lies on the disc or some mms away from it. (Infront of the union)

But he plans to use a ball valve as a trigger to the disk...

like this-

Chamber>ballvalve>burstdisk>barrel


His question is whether the ammo should go-

Chamber>ballvalve>ammohere>burstdisk>barrel

Or-

Chamber>ballvalve>burstdisk>ammohere>barrel

It goes chamber>ballvalve>coupling to the union>ammo>barrel.

David's were the other way around because they were designed as cartridges, and he was taking advantage of the tape not only to hold pressure, but to hold the BBs in in transit. Since BBs are far smaller than the size of the barrel, they won't have any trouble with traveling through the union, but a more tight fitting projectile could get caught up, and end up ripping off your barrel.

I'd precognize you go easy on pressure at first. I made a cannon like yours, even with a small chamber and 100 psi, it was nothing compared to just the ball-vave. Be very careful . And yes
Chamber -> ball-valve -> union + burst dic -> ammo in barrel.