I have a 1851 Colt .36 Cal with Colt ball marker both with documentation under WIlliam Randolph Hearst Collection. I inherited the Pistol and ball maker from my Grand Father, and most likely will never sell it, but I wonder its worth based on its connection to William Hearst.
With something like that auction at an auction house is really the only way to know for sure what it is really worth. I like and have 1851's, but even from the 1 photo you show I know that gun is out of my experience. Hopefully some one with more knowledge here will chime in. Can you post more pictures?
In my opinion, value would depend mostly on correctness/originality and how high a condition overall and possibly where in time the Serial Number puts it, and whether it is to be regarded as a Martial Arm or a Commercial one...with the WRH provenance probably not counting for much since WRH is not like say, 'Elvis' or General Patton or Teddy Rosevelt or other as-it-were 'positively' and energetically regarded figures of the past.