Thank you Researcher. I googled DuPont Oval, which led to two discussion threads you had participated in. What I gleaned from them was that the new progressive powders were introduced in shotgun loads in 1922 and enabled higher velocities with only slightly higher peak pressures by extending the period of high pressure, leading to potential failure of old twist barrels several inches forward of the chambers. Was there a change in fluid steel barrels at this time reflecting the change in powders? How long did it take for new american powders to be used in England or were the English also introducing progressive powders at this time? I can imagine conservative English barrel makers easily taking a decade to change the way they made barrels.
Any idea how DuPont Oval would compare to say 700X?
