Others may know for sure, but I can't find any indication that they were changed in any way. The only gun in question would be the medium frame (.32-20, .38-40, .44-40) because the small frame was .22 and the large frame was discontinued in 1894. So, with the only Lightning being made in 1900 using fairly weak cartridges, and the ammunition makers who had switched to smokeless duplicating black powder pressures, I really doubt Colt gave smokeless powder any consideration.
(Were it not for the collector value, my inclination would be to blow them all up, as they are the most frustrating, cantankerous rifles by a major company that I ever worked on. Maybe the repros are better, but I doubt it.)
Jim
