Hi Tomt........welcome to TFF!
It might have been the other way around.....that Andrew Fyrberg worked for Iver Johnson and then later, went into business for himself.
In 1886 and 1887, Fyrberg was issued 3 patents that were assigned to Iver Johnson.
339,301 April 6, 1886 Patent for Revolver of Iver Johnson, Reinhard T. Torkelson and Andrew Fyrberg
362,631 May 10, 1887 Patent for Revolver of Iver Johnson and Andrew Fyrberg
362,632 May 10, 1887 Patent for Revolver of Iver Johnson and Andrew Fyrberg
It's also believed that around the turn of the century, Fyrberg manufactured revolvers for Sears, Roebuck and Company.