That No. 508 Columbian is a nice heavy vise, alright, but there were yet larger, heavier ones built back before the war.
I've seen only a very few of the really big ones, doubtless they were so costly when new that only the Navy, the railroads, and a few mine or mill operations would have bought them.
Just for amusement, I dug out a couple of old machinery catalogs from the '20's and '30's, to get some specs on the seriously heavy vises which were available as an 'off the shelf' item, years ago....
The Columbian 508 was the largest of the '500 series' of standard machinists' bench vises. Its catalog spec listing was 8" jaw width, opening 13", and weighing 150lbs.
The Columbian 'heavy chipping vises', advertised as 'A careful study of conditions in railroad shops and steel mills has led to the design of this vise for extra heavy duty work. It is practically indestructible'. (note the 'practically'....I remember seeing a broken one in a scrap yard, some years ago, and wondering just what sort of men worked in the shop where that vise had been used)
The Columbian 'heavy chipping vises' were the No. 107, listed as 7" jaw, 11-1/2" opening, weight 218lbs., and the No. 108-1/2, listed as 8-1/2" jaw width, 13" opening, and weighing 268lbs. A rather serious tool, that......
One of the Columbian Co's competitors, the Reed Co., of Erie PA, 'went them one better' so to speak with their No. 109, listed as 9" jaw width, 13" opening, and weighing 290lbs. I've only ever seen one of those, which was salvaged from the maintenence shop in a large saw-mill, after the mill itself burned down.
And then there was the 'Trenton chain vise', basically the old style of blacksmiths' 'leg-vise', except that it used two screws connected by a link-chain, for parallel opening.....some of those were literally of 'monstrous' size.....intended for the very heaviest of hand forging work, presumably.
cheers
Carla