Thanks Baffled!
I've got .010" clearance betweent the core and the tube. Other stats: main chambers are .600", with .060" walls between. The wall thickness between them and the outer edge of the core is also .060". This ends up giving you an offset from centerline of .100". The wall thickness of the main chambers to the secondary chambers is .050". Mouseholes were .200" dia.
I didn't really plan on the steel sleeve like you did, thinking this will be a low volume shooter but I wish I had now after seeing how much gunk is blasted through this thing.
Which leads me to another thing. I was able to run a couple of shots through it before drilling the holes to the secondary chambers. I've never shot a suppressed .22 pistol before-just rifle, but the first round pop was significant and and it seemed kind of loud to me. I then drilled out the mouseholes and tried it. All I can say is GROOOOVY! After a few little test firings I can sometimes tell that there is a little first round pop, and other times I don't think there was any. In the end I'm very pleased with it. I really want to compare it next to a commercial can and see how it does.
For anyone thinking of using this design, here are some watchouts I've come across:
--If you thin it out as much as I did with .050-.060" walls, don't plan on putting any large side to side forces on it. If you put the tube on one end as a lever you can begin to feel some flex in the stack.
--With that in mind, I didn't really design in any good take-down features. Instead, i'm going to have to keep the threads and tube ID well lubed with anti-seize and semi-dissassemble it every 50-100 rounds to make sure it doesn't seize up.
--The O-rings actually work. Without them there were gasses sneaking out.
And now for some pics:
It's not as visible as I hoped in the pictures, but most of the gases hit below the exit hole and are vectored up and outward. The primary flow of the gases is coming downward from 1st chamber and then is splashed upward in the 2nd across the exit hole. Stuff is then slowing down and getting deposited on the top and back wall of the chambers. There are also crescent moon shapes of black deposits on the wall of the tubing where it meets up with the back top portion of the chambers. You can see this when you take it apart and look down the inside of the tube.
This is really cool. The end cap chamber has a large deposit of stuff on one side but not the other. This lines up across from the bottom of the last circular chamber. This means that it is directing the gasses up very well accross the bore path. Very cool. My design-fu is feeling strong.
Here's a view of the mouse holes since I didn't post this last time. The primary chamber got access to two of them, while the last chamber didn't get any. Gotta have priorities, you know?
Enough of this. I'm off to the range.
. Have you drilled any of the "mouseholes" yet? What design are you using for them?
Lucky you did it in aluminum, you'd have to mortgage your house to buy enough 1/8" end mills to cut thoses grooves in stainless. 
