SpudFiles

What would you suggest for bracing two chambers together?

The gun is configured with the barrel in between the two chambers and it is an interchangable barrel system.

Basically it is configured like OoO (only the barrel is up a bit higher). It is 4" PVC chambers that are 5' long each. they are only connected by 2" pipe so it scares me picking it up. I am also hoping this can help when the gun is recoiling to stop the chambers from turning inwards( | i | to / i \ ) where | and / \ are chambers and i is the barrel from top down (for more orientation, think of the dot above the i as the projectile after leaving the barrel)

Portability is nice, safety is important

Perhaps wood?

pvc tees bored out allowing the tees to slide over your chamber and then some pipe to connect them and maybe another tee to connect the barrel?

Maybe it is just me but i do not quite understand what exactly you want, could you draw a diagram?

I would do it this way:
http://www.spudtech.com/detail.asp?id=53

Wood as support and those metal strips to hold it.