Some 40+ years ago I had a 20ga Ithaca Flues. I knew absolutely nothing about the frame cracking problem at the time & it was marked "Smokeless Powder Steel". I did have it rechambered for 2 3/4" shells but I believe they were standard cone length, seems long cones had not gained notoriety at the time. For several years it was fed a steady diet of 2½DE-1Oz in both factory & reloads. Insofar as I could tell it never suffered any harm, though I would not recommend those loads for it today. Since the 1" location for measuring max pressure was sellected to make "Certain" it caught the max, I would not really expect cone length to have a lot of bearing on max pressure. This has I think been pretty well proven. What is much more realistic is the pressure does not "Fall" from max quite as fast with a short cone as with a long one. Since total bbl time is no more than .003 of a second, the length to traverse the cone is likely measured in the millionths, it utterly amazes me how many people can "Feel" the difference.
