2" Chamber to 1/2" Barrel old school Hair spray

[tatfree]

I just picked up an Aluminum 2" Cam and groove coupler yesterday,

Like this one.
http://www.spudfiles.com/official_pics/breech01.jpg

I am going with an Aluminum 2" Chamber down to an Aluminum 1/2" Barrel then Anodize the whole thing when I'm done ( Mostly for looks ).

What's the most efficiant Chamber to barrel ratio for a 2" to 1/2" barrel ? I have looked on here and don't see much on this when using the old school design of Hair spray fueled ( Aqua net is my favorite ).

Barrel length ?

I was also thinking of going with a 3/4" barrel, but have not settled on that one yet.

Barrel length ?

The Ignition will be placed in the rear of the chamber using a single isolated wire in and it will ark against the Aluminum tube probably using a 1/8'' gap.

Thanks for the help.
P.S this is my first post in the combustion forum.

[tatfree]

Okay thanks guy, looks like I'll make it a 4 to 1 ratio chamber/barrel for maximum efficiency as many of you PMed me with to do.
Keep the PM's coming.