Eureka! I guessed the right box of as-yet unpacked stuff from our move and found my files. As a result of which I now have my original sources at hand, and can comment as follows:
1. Pressure readings from the early 1930's. The American Rifleman, Sept 1931, included an article by Merton A. Robinson, ballistics engineer, Winchester Repeating Arms Co. Title: "Standard Shotgun Pressure Barrels". The article describes quite thoroughly the crusher method of pressure testing, and includes photos of pressure barrels then in use by Peters, Hercules, Western, Remington, Winchester, Du Pont and Federal. Although the barrels are of somewhat different designs, they are ALL the old crusher barrels. Therefore, any pressure measurements they expressed as psi would, in fact, have been LUP.
2. The Damascus "myth": My files contain another "Rifleman" article: a 2-parter (July 36 and March 38) by A.P. Curtis, who had been in the firearms business since the mid-1890's with various firms such as Syracuse Arms, Hunter (superintendent and factory manager), Winchester (foreman of all barrel shops), Ithaca (general manager), and was with Iver Johnson as assistant to the president when he wrote the articles. The article is entitled "Advantages of Short Shotgun Chambers".
I think many of us realize that the Damascus "myth" was drummed into our heads (as was the short chamber myth) by virtue of the warning printed on shotshell boxes. How did that warning come to be? Per Curtis: "SAAMI, assembled in serious conference on March 26, 1937, passed the following resolution: 'That an appropriate warning label be placed on all boxes containing smokeless powder shells, cautioning the consumer against using them in short chambered guns and also in guns with Damascus barrels and guns not in first-class condition'." The motion was made and seconded by representatives of two powder companies. That same conference also passed a resolution requiring: "That all guns be marked so that the consumer will be able to tell the chamber length, as for example by marking 2 3/4 inch chamber etc." That rule seems to have been followed on guns with 2 3/4" or longer chambers, but not on those with shorter chambers. And Hunter Arms, for one, was still producing short-chambered 16's at that time. Anyone ever see one factory marked 2 9/16"???
Although we recognize that neither chamber length nor the material of which the barrels are made, in and of themselves, constitute danger to those who proceed with a certain amount of caution, the warning--given the time at which it was issued--makes a certain amount of sense. By then, the new Super-X and similar shells, which increased pressures, had become commonplace. At the same time, however, dozens of loads were readily available, in all gauges, that were made up in shorter shells, appropriate for short-chambered guns which had lower proof standards than were then current for 2 3/4" guns. And it probably would not have been a good idea to fire a steady diet of Super-X 2 3/4" shells through a short-chambered gun, whether Damascus or fluid steel, because you have both the greater pressure generated by a slightly longer shell, plus the greater pressure developed by a "hotter" modern load.
The result being, of course, the over-generalization that you should not shoot any longer hull (regardless of the pressure of the load) in any shorter chamber, and you shouldn't shoot any smokeless load in any gun with Damascus barrels.
Those of us who have participated here pretty much from the beginning, however, clearly remember that there was a very strong "Damascus roulette" contingent involved in our discussions. And that we still find those who think Damascus guns are generally unsafe, and who think any longer hull in any shorter chamber represents extreme danger. (Darn. I just shot 3 rounds of skeet this morning with a 2 1/2" BSA 12ga: 2 3/4" Remington hulls, Extra-Lite powder, 7/8 oz shot . . . and I still have all my fingers.)
