Sgt. 1st Class James O'Leary, a Warrior Transition Unit Soldier, sits on a fully-restored WWII German anti-aircraft weapon at the Army ADA museum. The MK103/38 German 30mm Flak cannon, also called the "Jaboschreck," or "fighter-bomber terror" gun, wa... (Photo Credit: U.S. Army) VIEW ORIGINAL

FORT SILL, Okla. (Aug. 7, 2014) -- The Army Air Defense Artillery Museum has many unique and historic weapon systems and artifacts from nearly 100 years of air defense artillery history.

Aug. 1, the museum staff installed a rare and special weapon that is the last remaining example in the world an MK103/38 German 30mm Flak cannon, also called the "Jaboschreck," or "fighter-bomber terror."

Jonathan Bernstein, museum director and curator, spoke to the crowd gathered for the installation ceremony about how special the German gun is to the museum's collection.

"We now have another unique artifact to add to the collection here. As a museum historian this is a thrilling moment that has taken a long time to complete," Bernstein said. "This has been an 18-month process -- six months of research and a little less than a year of restoration by an incredible team."

Bernstein handed out certificates to the six team members who worked on the restoration: Zane Moeller, exhibits specialist for the Fort Sill Directorate of Museums; Sgt. 1st Class James O'Leary, a Warrior Transition Unit Soldier; retired 1st Sgt. Mike Tomany, an ADA museum volunteer; Staff Sgt. William Miller, 31st ADA Brigade; Maj. Luke Sparks, 1st Battalion, 30th Field Artillery; and Brandon Atwood, an ADA museum intern.

"We know the Germans ordered 3,000 of these MK103 guns 2,000 of them from the Rheinmetall Borsig factory, and 1,000 from the Suhl factory. Only 40 of them ever saw combat with two battalions of the 17th Panzer Division in Yugoslavia from February through May 1945. This is serial No. 175 from the Suhl factory. It was an early production from the second run but other than that we don't know the combat history of this particular unit," Bernstein said.

"It is a missing piece of history from the second world war, and it is a weapon our fathers and grandfathers fought with in war. They waited to see it in action, but it was never really saw action in large numbers," said Col. Ingo Kresser, German Air Force liaison officer at Fort Sill. "Of course, on the technology side, it is the forerunner of more modern weapons, which you can see in the three different sets of aiming devices. There are the optical devices, which point towards the modern weapons to come. It is an astonishing piece."

Bernstein said a lot of research went into the piece before they could even begin the restoration. Back in 2012 the ADA museum got the carriage and mount from Aberdeen Proving Ground, Md., where it had sat out in the elements for over 70 years. But, there was considerable confusion as to what kind of weapon it was.

At first, Aberdeen told Bernstein it was a 37mm cannon. Then when they looked closer, they said it was a 20mm cannon.

When the carriage and mount arrived at Fort Sill, Bernstein discovered it was not for a 20mm weapon, but was for a 30mm cannon, and the actual cannon was not with the carriage and mount assembly. It would take almost two years to discover that the 30mm cannon had been sent to the National Air and Space Museum in Washington, D.C., back in 1990.

So in January of this year the real work began, as Bernstein's team began tearing down the weapon to do the restoration.

"We completely tore it down. Then we sandblasted the entire gun and removed all the rust. Surprisingly the internal workings were in very good condition, just a little bit dirty. We cleaned everything up and about 99 percent of the original parts were reused. The only thing we had to replace were the bolts that actually mounted the gun to the chassis. Those were long gone," Bernstein said. "Now it is finished and is the only one that exists in the world."

Bernstein pointed out that even the tires and inner tubes on the carriage are the original ones produced in Germany more than 70 years ago.

"They were in great shape. All we did was replace the valve stems, aired them up and they held. That was truly amazing," he said.

Col. Christopher Spillman, ADA commandant and chief of ADA here, praised Bernstein and the team of museum volunteers.

"I just want to say that I am impressed by the work that you and your team have done. This truly is an important addition to the ADA museum. It is very unique that we are the only museum on the globe that has this particular weapon on exhibit. Well done to you and your team," Spillman said.

"There were projects in the development phase to put a quadruple set of these on the Tiger tanks and also a twin gun configuration on other vehicles. You can say that, for the cannon-based weapons, it was a large step in technology. This is a very moving moment for me as a German," Kresser said.

"All of the restoration was done at the exhibit shop right here on Fort Sill. It was painted in accurate WWII colors that we got from a vendor that specializes in military vehicle paints, and it was matched exactly to the original colors," Bernstein said. "It has been so much fun researching the history of this gun."

The MK103 "Jaboschreck" can be seen at the Fort Sill ADA Museum in Building 1506 on Bateman Road. Museum hours are 9 a.m. to 5 p.m. Tuesdays through Saturdays.