U.S. Revolver Co. was not actually "taken over" by Iver Johnson; it was a name used by IJ on guns they made originally to use up old parts after their safety model (with the transfer bar) came out. They later kept the name for a line of revolvers sold through mail order companies, while the Iver Johnson brand was sold only through distributors and dealers. Oddly, the U.S. brand was not significantly lower in cost, which probably reflects the huge markups and profits the mail order companies enjoyed in the period around 1900.
Jim