Since most of us are unlikely to run across a copy of Wright's book, do you suppose you could give us a quick rundown of what he wrote about chamber ringing? Please?
He believes it is a result of airspace within the load. The airspace allows for a pressure wave to be created. The theory is based on Paul Vieille's (1890) theory of "Wave" pressure. Burrard in The Modern Shotgun (1948) summarized Vieille's theory to explain what happens inside a cartridge case. Vieille proved that the high end pressures were caused by the movement of the hot and very elastic powder gases When the powder is ignited at one end, a wave of high speed gases accelerated through the airspace. As the wave hit the solid end it stopped, and as the following gases piled up behind, the forward layers were compressed violently causing a localized area of high pressure.
(You already mentioned this book by Dell and it is in Wright's write-up on Chamber Ringing): Charles Dell co-wrote The Modern Schuetzen Rifle (2nd Edition 1999) with Wayne Schwartz. Charles Dell was able to backup Vieille"s theory. That is, chamber ringing is caused by high velocity gases hitting the base of a stationary bullet. This creates a very thin, but high pressure gas area at the bullet base, and when this exeeds the yield strength of the chamber steel, a ringe is formed.