According to an article in the American Rifleman several years back, semi-smokeless powder showed up about 1894. We have a photo of my great grandfather, dated OCT 1900, holding the gun in question (pheasant hunting). This is one of those common , "run of the mill" Belgian made '"farmers' guns". Has an interesting lockup which appears to be a double dog leg/Greener combination. It's still nice and tight.
As previously noted, my family has put cases & cases of modern, smokeless light loads through it since the mid 1930's. Besides the "fluid steel" stamp there's also the Royal Damascus mark, which is nothing more than a printed pattern on the barrel.
Has the common "Wm. Moore" name, trying to make believe that it's a high end English piece.