Cloud BBMG Mods

Thoughts On Getting Higher Muzzle Velocities From A Cloud BBMG

I've been fiddling with a similar idea for a cloud design. Basically, add an O-ring or short piece of rubber tubing to the breach end of the barrel. The ID of the tubing is a little less than the OD of a BB. Kind of like these two crappy drawings;

The block in the diagram just represents a small section of the chamber wall. The barrel would be positioned high in the cloud chamber, not low like the drawing suggests.

My O-ring drawing looks like a washer which, come to think of it, might work.

The O-ring is sized so that its OD matches the OD of the barrel but its ID is less than the OD of a BB, say a 1/4"OD by 1/8"ID O-ring. An alternative to the O-ring is a short length of soft rubber tubing, like Tygon. The tubing may last longer than an O-ring.

The generally idea for the firing cycle is;

The trigger is pulled, air starts to flow at high velocity into the chamber (and out the barrel) and the cloud/vortex chamber works normally.
Eventually a BB loads into the beginning of the barrel but is stopped by the tubing (or an O-ring), sealing the barrel.
Pressure builds in the chamber, the cloud/vortex stops working since there is little/no air flow out the barrel.
Eventually the pressure in the chamber builds enough to force the BB through the tubing.
Since the tubing alone doesn't close off the barrel, air pressure blows the BB out the barrel.
The barrel is now unsealed and dumps air, rapidly lowering the pressure in the chamber.
As the pressure in the chamber drops, air flow into the chamber increases and the cloud/vortex starts to work again.
Eventually a BB loads into the beginning of the barrel but is stopped by the tubing, sealing the barrel... and the cycle repeats.

I think the same idea might work on a vortex design.

The tricky part is getting tubbing with the correct ID. So far, I have 1/4"OD x 0.17"ID and 1/4"OD x 0.125"ID tygon tubing.

Problem with 1/4"OD x ~3/16"ID tubing in a 1/4" recess is the tubing can't expand to let the BB pass.
Increase the recess to 3/16"D so the tubing can expand to let the BB pass. And perhaps use 1/4"OD x 1/8"ID tubing
Move the tygon to outside the chamber so it can expand. Indeed pressure behind the BB will be working against atmospheric pressure instead of the pressure in the chamber.

An easy way to flare tygon tubing is to push it onto the hot tip of a hot melt glue gun.

The drawings belopw outline the current project. To increase the area that supports the barrel, and to make assembly and diassembly easy, I filled a two inch clean out plug with bondo.