Keith Cangelosi was shocked when he read a magazine article about the only rifle still in existence that is known to have been used at the Battle of New Orleans in 1815.

That's because someone had stolen the same rifle from the New Orleans museum Cangelosi leads, Confederate Memorial Hall, more than three decades ago.

The article, published in the National Rifle Association's magazine in 2013, said the gun belonged to a private collector who had acquired it from a well-known antiques store in New Orleans' French Quarter.

Cangelosi first thought about trying to get the rifle back by going to court. But then, a conversation with an FBI agent kicked off a federal investigation. 

It turned out the collector had acquired the flintlock rifle without realizing it had been stolen. And on Monday, on the 203rd anniversary of Andrew Jackson's victory over the British near present-day Chalmette, the rifle finally came home to the museum on Camp Street. 

The FBI reckons the museum could fetch as much as $650,000 for the rifle, but Cangelosi said he considers it priceless.

The rifle originally belonged to William Ross, a local militia member who carried it as one of Jackson's volunteers.

Scholars often cite the American long rifle carried by Ross and other Jackson-led troops — it was relatively accurate for the time — as a key factor in one of the most decisive victories in U.S. military history.

"Not even the Smithsonian has one of these," said Cangelosi, the president of Confederate Memorial Hall's board of directors. "We're glad to have it back."

Ross survived the fight and, after his death in 1835, left the rifle to his son James. James Ross apparently had the gun engraved with the words, "This rifle was used by my Father Wm. Ross a member of Cap. (Thomas Beale's) Company of New Orleans Riflemen in defense of N Orleans in 1814 & 1815."

William Ross' grandson, Elijah Ross, a Confederate soldier, later inherited the weapon and donated it to Confederate Memorial Hall three years after the museum opened in 1891.

For many years, the museum stored and displayed the .38-caliber rifle, which was built by renowned Virginia gunsmith John Jacob Sheetz.

Decades ago, however, someone made off with it, though no one can say exactly when. 

The museum had no idea it would get the weapon back until someone spotted the American Rifleman article, which chronicled how a couple named Robert and Linda Melancon had acquired the gun in 1982 from James H. Cohen and Sons Inc. on Royal Street.

Cangelosi said the museum was reviewing whether it could turn to the courts to get it back when an FBI agent named Randolph Deaton called.

Deaton, who specializes in crimes involving artwork and antiques, told Cangelosi that the bureau had recovered a number of items that had been stolen from museums across the country, possibly including Confederate Memorial Hall.

It turned out that none of those items actually came from New Orleans. But, while the museum had the FBI's attention, it did ask the bureau for help in regaining Ross' rifle.

The FBI agreed to intervene, receiving help from Louisiana State Police. In November, a team of investigators led by Deaton obtained a warrant to seize the rifle from what the FBI would describe only as a home in south Louisiana.

The FBI declined to identify the Melancons by name, though they were mentioned in the magazine article. But the bureau said the people who purchased the weapon were "extremely cooperative" with the investigation and appeared to "have had no knowledge of the rifle's theft."

The Melancons couldn't be reached Monday. The Cohen store didn't immediately respond to a message.

During a news conference at the museum Monday, Deaton said he doesn't believe anybody is facing arrest or prosecution in the case.

Meanwhile, the highest-ranking FBI agent in Louisiana, Eric Rommal, suggested the case's primary purpose was reuniting Confederate Memorial Hall with one of its most prized artifacts.

As officials at the museum removed a veil covering the rifle and its 42-inch barrel, Rommal said, "A significant part of New Orleans history has been recovered."

Follow Ramon Antonio Vargas on Twitter, @RVargasAdvocate.

(504) 636-7433