I don't doubt there may have been periods when other companies made brass 12 m/m .410-bore shells. I stated that my Winchester paper was very thin thru this period.

As to 3-inch brass 10-gauge shells, they are offered in all my UMC paper from 1903 thru 1914, as are 2 5/8", 2 3/4", 2 7/8", and 3 1/4". After 1918 they only catalogued 2 5/8" and 2 7/8" brass 10-gauge shells, and by 1926 only 2 5/8".

I know from researching Fox and Parker records that both those companies built guns with features that were not catalogued so I can certainly imagine that the even though an ammo company only catalogued primed empty brass cases, that they would load them up if the customer ordered it.