As 'blacksmiths' or 'leg' vises go, that one is relatively late production, quite possibly as late as the 1940's, as may be seen in its smooth 'drop forged in forging dies' configuration, and the simple 'style' of the screw and nut.
That one appears likely to be of the common 'Columbian' make, and may have a 'letter C in a diamond' marking somewhere. The bench mounting plate, if original and not a shop-made replacement part, appears typical of the later Columbian production.
Depending on its size/weight, that vise should certainly have some value, for any active blacksmith, especially if it is one of the medium to larger sizes, 6" or 8" jaw width.
cheers
Carla