How about we conduct our own tests?

I can provide the tube (turned to appropriate contour), and then we need someone with the proper equipment to measure any expansion as the bullets are driven down the barrel.

I would think that person would also need a lathe to continue turning down the outside of the barrel to thinner and thinner wall thickness to make the test as comprehensive as possible.

How about it: do we have any retired engineer types out there with some good measuring tools and extra time on their hands?