There has been a lot of corruption of the stories and artifacts surround Tombstone history, so it's very hard to know what the truth is, including that of the guns used in the shootout behind the OK Corral.  As to Wyatt Earp, we know he owned a number of guns in his life, but the one in the story I linked here the other day is generally believed to be the one he used in that famous event. 

Here's another take on that subject.

http://arizonasonoranewsservice.com/mystery-wyatt-earps-guns/

I believe there is also a gun on display in Superior, Arizona said to be his.  If so, a possible connection would be to Mattie, Wyatt's second wife.  He essentially kicked her out of Tombstone because she was a drug addict, and she made her way north living as a prostiture at Pinal, the Silver King mining camp (very near what later became Superior).  She died there of an overdose, perhaps as a suicide.  In subsequent decades her grave was so often damaged by souvenere hunters, the forest sevice moved it to a secret location.