Researchers are trying to crack the mystery surrounding the discovery of a weathered, rusted, but once-prized Winchester rifle in the mountains of remote eastern Nevada.

The Model 1873 gun, manufactured in 1882, was found leaning against a juniper tree on a rocky outcrop in Great Basin National Park during an archaeological survey in November.

Nichole Andler, the park's chief of interpretation, said officials may never know when the .44-40 rifle was placed there, but it is possible it could have been left undisturbed since the 1800s.

The area along the Utah border has a history of mining, ranching and hunting, she said, and park researchers are scouring historical documents to learn who might have owned the rifle.

"I would say the possibilities are wide open as to who owned the rifle and why it was left there," Ms Andler said. "It leaves a lot to the imagination and it may be a mystery that's never solved."

Herbert Houze, former curator of what became known as the Cody Firearms Museum at the Buffalo Bill Centre of the West in Cody, Wyoming, said Winchester Model 1873 rifles such as the one found in Nevada were so valuable that whoever owned it leaned it against the tree - then was unable to find it.

"You just don't leave a gun like that there," he said.

The rifles, which sold for $35-$50 in the 1880s, now can fetch up to $15,000 in excellent condition. They were among the most popular guns on the Western frontier.

Hollywood made a 1950 Western, Winchester '73, starring James Stewart, which told the story of the journey from owner to owner of one of the sought-after guns.

After seeing photographs of the rifle, Mr Houze said it went undetected for so long because it blended in so well with its surroundings.

"People probably have walked right by it," he said. "It was a one in a million chance they looked at it the right way and found it."

The unloaded rifle's wooden stock was cracked but still intact, while its barrel was rusted. Its serial number was still visible, which allowed experts at the Buffalo Bill Centre to determine it was made in 1882.

Mr Houze says he is thrilled by what he called the "rare find" in Nevada, which will eventually go on permanent display at the park.

"It's one of the most exciting gun discoveries I've ever heard of," he said. "I'm just tickled pink the gun got found."