Is the American EC nitro powder the old "Magic" smokeless powder? I had heard that making the twisted steel into barrels was a "lost art" ... and that is a true crying shame. Every one of those barrels is a work of art unto itself! (Sigh) I never was able to pick one up for myself ... and they are truly works of art!
You're not confused, John. This gun was manufactured and originally proofed for nitro powder as were many Damascus barreled shotguns. In Europe many Damascus guns are nitro proofed a fired with modern shotgun shells.
My other Damascus gun is my Parker GH which was manufactured in 1924. It was test fired and proofed with the same loads Parker used on their fluid steel guns. Damascus guns were manufactured into the 1930. The would be still made today but the labor cost made them way to expensive when compared to fluid steel and no know has the skill and knowledge to produce Damascus barrels. It is a lost art.
Only shooting black powder in Damascus barreled guns is kind of an old wive's tale. I'm sure neither of my Damascus barreled shotguns has ever seen a black powder load.
BTW: that is 33 grains of American EC nitro powder. American EC was bought out by DuPont before WWI.