I have read that Dixon was not shooting his own rifle. It was a new one that had been shipped in for somebody. He later said that the shot was just a lucky one.
The site was originally built in 1843 by Bent St. Vrain and Company as a trading post but the Indians were hostile most of the time it was in operation. Bent blew it up and left Texas in 1849.
Kit Carson led US troops there and fought a battle with Indians in 1864. The second battle was the one Dixon was at in 1874.
There are lots of articles and a few books about the fight in 1874 and various accounts give the range of the shot at from 1000 yards to 1538 yards. Dixon said he shot from a rock outcropping that was used frequently in shooting contests.
