1930: I had in fact forgotten rc.moto's post (sorry guy) , I stumbled across the pic of the Champion while looking for something else...Yes, I should have reread the entire thread..
However the context is different and adds hints....Putting the two together leads me to a different conclusion than either alone, Mosco probably didn't make them, Champion probably made them at some point and sold them to others, so probably also mosco, 'champion pattern' hints that someone else was also making similar ones.....and the Winchester ones basic similarity but slightly different pattern leads me to believe that more than one company was making that general style also...
Still don't know anything about what is in fact stamped on the OP one tho...
Chas a Strelenger catalog[1896] also shown "the Champion" screw driver, with the notched ferrule.
Sears,1897,P94
EDIT: In my 1897 reprint, it seems to be Pg 80...