Descendants of Earp say the Arizona lawman carried the gun during his time in Tombstone and possibly even used it during the shootout at the O.K. Corral.
The firearm was estimated to fetch $150,000, but far exceeded that price when a phone bidder from New Mexico bought it for $225,000.
"I think we crushed it," said Josh Levine, owner of J. Levine Auction & Appraisal. "I was happy the fair market really decided what these items were worth. I had no idea whether these items were going to sell."
The authenticity of the Colt .45-caliber gun was in question because its serial number had been rubbed of and the gun's barrel, cylinder and grips had been replaced.