binding barrel bolt meets a carriage bolt

[magicniner]

okay -

so this seems like a viable solution. however, i would imagine that after pressing in the drive screws - they would probably 'slighting' bulge the inner tube - thus creating friction for the center barrel to rotate smoothly?

is this correct?

No, it's not.
Drive screws have a fast outer helix with a relatively high sharp profile, they are designed specifically for blind holes where the relative sizes can be chosen such that material distortion stays local to the hole walls, among other things they are commonly used to fix data plates to castings.
You could make the holes in the bracket a tighter fit to give a lot of hold and the hole in the tube the right size to prevent rotation and give adequate retention without distortion of the outer.
It's your job to experiment with drive screw size, tube hole size and wall thickness to get the materials behaviour you require for your application.