NEW YORK (NYT NEWS SERVICE ).- A rare Revolutionary War-era rifle stolen from a display case at Valley Forge State Park nearly 50 years ago has been returned to its rightful owners.

The 5-foot-long rifle was made in 1775 by Johann Christian Oerter, a master gunsmith at the Moravian settlement of Christian’s Spring, near Nazareth, Pennsylvania. Only a few signed and dated rifles from that era survived, and Oerter’s work is considered among the finest. A similar Oerter rifle belongs to the British Royal Collection Trust.

The FBI’s art crime team and other law enforcement officials returned the antique on Friday to the Pennsylvania Society of Sons of the Revolution during a ceremony at the Museum of the American Revolution in Philadelphia. It will go on display there Wednesday.

“The Christian Oerter rifle exhibits exemplary early American artistry, and is a reminder that courage and sacrifice were necessary to secure American independence,” R. Scott Stephenson, the museum’s president, said in a statement.

Officials said the rifle was recovered with the help of Kelly Kinzle, an antiques dealer in New Oxford, Pennsylvania. Jay Robert Stiefel, a lawyer for Kinzle, said that his client bought the firearm last year as part of a collection. As he researched it, he found a reference to a stolen Oerter rifle in a 1980 book by George Shumway, an expert on antique long rifles who died in 2011. Kinzle then turned the rifle over to the FBI.

When it was stolen in October 1971, the rifle was on loan to the Valley Forge Historical Society, the predecessor of the Philadelphia museum.

It was taken in broad daylight from what was thought to be a theft-proof display case at the visitor center at Valley Forge State Park, about 20 miles northwest of Philadelphia.

Now administered by the National Park Service, the area was the site of a Continental Army encampment in the winter of 1777-78, under the leadership of Gen. George Washington. The period was a turning point in the war, as the soldiers became a coherent fighting unit, and Valley Forge became a symbol of the fight for independence.

An article in The Philadelphia Inquirer on Oct. 26, 1971, reported that the burglary had occurred weeks earlier but was not publicized because of concerns that the thief might panic and discard the rifle. At the time, it was insured for $15,000, roughly $95,000 today.

The thief managed to pry open the display case using a crowbar or similar instrument shortly after the museum opened at 9 a.m. on a Saturday, The Inquirer reported. A Boy Scout on a tour with his troop noticed it was missing some time later.

On Friday, the Montgomery County district attorney, Kevin Steele, noted that in 2009, the local police reopened an investigation into various burglaries and thefts of historic artifacts from Valley Forge in the 1960s and ’70s. They teamed up with the FBI and other agencies and sought out collectors and scholars to help. Steele said that the local authorities remained committed to trying to solve those crimes.

The Moravian church is a Protestant denomination, and many adherents settled in Pennsylvania in the 1700s. Makers of “Pennsylvania rifles,” which are also called “Kentucky rifles,” had a strong influence on the development of American firearms.

In the 1980 book “Rifles of Colonial America, Vol. I,” Shumway wrote that Oerter was an apprentice of Andreas Albrecht and took over from him at 19. Based on what could be serial numbers on surviving weapons, Shumway wrote that Oerter might have created 16 guns a year until he died of illness at 29.

The recently recovered Oerter rifle has an elaborate brass wire inlay, and Oerter’s name, the year and location of its creation are engraved on top of the iron rifle barrel. Another name, W. Goodwin, is carved into the rifle’s maple stock and may refer to its original owner.

Another Oerter rifle with raised carving on the stock recently fetched more than $200,000 at auction, said Michael Simens, an antique weapons dealer in Willoughby, Ohio, who runs the site historicalarms.com.

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