The reason I have doubts about the thin barrel wall theory is that I think the bullet would have to be swaged down upon entering the bore, which occurs in the heavier walled shank of the chamber area. By the time it gets to the thin walled part of the barrel, I should think the bullet is already at bore dimension, and thus, have no impact on causing the tubes to "bulge". If the bullet were truly causing a "bulge" that travels down the exterior of the barrel, the chamber pressure would be sky high, and would have to remain higher than normal, for the entire time that it's in the barrel. But, that's just my opinion.

I should think the whole thing should be easily(but not cheaply!) proved/disproved by attaching strain gages inch by inch down a test barrel contoured like a double rifle. Fire some control rounds of conventional lead cored bullets, and then fire the mono's, and see what really happens.

Jeff