PICATINNY ARSENAL, N.J. -- For nearly two decades, the item had served as a doorstop at the home of a New Jersey resident.When he decided to move, the resident approached a New Jersey museum to determine if it wanted the shell-shaped doorstop as an item of historic interest.Jeff Ranu, the historian with the U.S. Army Armament Research, Development and Engineering Center at Picatinny Arsenal, later received an email from the museum curator with the words "Mystery Item" as the subject line.The email continued: "It weighs about 15 pounds. Do you know what it is? Is it something which could be live?""The statements elicited both curiosity and concern," Ranu recalled. "The photo provided depicted a side view of what appeared to be an old artillery shell, which gave an indication of the scale of the shell."Ranu knew that handling explosive ordnance is inherently risky. "The risk is compounded when the condition of the munition is unknown due to age-related corrosion, has an unknown transportation history, and is a non-standard design," he said.The danger of handling an item with the potential to detonate is such that only personnel trained to render munitions safe, such as Army explosive ordnance disposal units and police bomb units, should be alerted when suspicious items are discovered.That precaution is even more relevant as more civilians are coming into contact with historic ordnance items that were retained by service members who served in past wars and conflicts. "Search and turn in" was less stringent during the early to mid-20th century than current regulations and operating practices, especially when considering the number of military discharges at the end of the World War II."Many veterans brought home souvenirs from their service, ranging from hand grenades to medium caliber ordnance," Ranu noted.The World War I generation is all but gone, and the World War II generation is shrinking steadily, but these souvenirs are now being discovered by family members with increasing frequency. Many people coming across these items have no prior military training and aren't aware if there is a danger associated with them.After studying the photo provided by the museum, Ranu's first thought was that this might be a World War II-era armor piercing shot.The M62A1 76mm (3") APC (Armor Piercing Capped) shell came to mind as a potential identity. In order for this item to be part of this World War II shell, it would have to be a projectile without the ballistic cap installed.Ranu was able to retrieve ordnance round charts from 1948 stored in the archives. ARDEC Technical Data had the M62A1 product drawings available in electronic format, so retrieving the drawing for comparison was possible.The M62A1 Projectile drawing numbers were retrieved and the electronic copies obtained from Technical Data were consulted first. A comparison of the projectile length on the drawing was made with the length of the mystery item in the photo.It was immediately apparent that the mystery item was not the M62A1 3" shell. The uncapped shot was only 8" long, while the mystery item was along the lines of 11" long. Even with the cap installed, the projectile would be only 9" in length. Adding the windscreen installation, the projectile was now over 13" in length. This could not be the World War II APC. The safety of the mystery item was also a concern. The M62A1 APC had a fuze and an "Explosive D" bursting charge installed in the base.Ranu also had 18 years of engineering experience in high explosive munitions work. "The prospect of live energetic materials present in a shell with visible corrosion and unknown transportation history was troublesome," Ranu said.The possibility that rough transport could have armed a live fuze with a bursting charge was an immediate concern. The photographs provided by the museum curator did not show the rear of the shell, where a fuze would be installed, so the safety status could not be determined.Ranu contacted the museum curator, and relayed the importance of providing a photo of the rear of the shell. He also explained how a fuze, if present, could set off a bursting charge.Ranu told the curator that he could not make a positive identification of the shell since there were no markings visible and the diameter was unknown. Ranu asked the curator to carefully photograph the rear face of the shell and send it via email. The historian further noted that if the back was hollowed out, the shell was likely just a steel part. He also mentioned that if there was anything assembled to the back, or if the back was open but it appeared that the shell was filled with a substance, to treat it as live.Ranu also cautioned not to attempt to disassemble a fuze to see what was inside, but let him know immediately, and that ARDEC explosive ordnance disposal technicians would need to be notified and consulted.The museum curator sent back more photos showing the condition of the shell. The new information indicated that the back of the shell was not hollow. The photo of the rear of the shell showed that at least no fuze was assembled to the shell.A fuze would have been visible as a protrusion from the back of the shell, as in the M62A1. "The absence of a fuze was a relief, but not a guarantee that the shell was completely inert," Ranu said.He consulted with the ARDEC senior research scientist, who suggested the possibility that it may be an older 3" uncapped AP shell, the M79 AP shot.Ranu was able to obtain the drawings from ARDEC Technical Data, and used the assembly and component drawings listed to piece together a drawing package.The M79 Metal Parts Assembly drawing clearly depicts a tracer in the back end of the projectile, but it does not protrude and appears flush with the back of the shell."The amount of corrosion on the back of the shell could be masking a tracer installed, leaving the possibility that the shell may not be completely inert," Ranu said.Ranu then contacted ARDEC Explosive Ordnance Disposal to obtain its assessment, and provided his preliminary assessment and all background information.EOD concurred that the shell appeared to be a solid shot at first look. But they could not verify its safety without a physical inspection of the item.The museum curator made the proper requests to have ARDEC EOD dispatched to the location of the mystery item, inspect the item, and render it safe if necessary.The EOD unit performed an inspection of the shell on site with a portable X-ray device. The concern was that multiple layers of corrosion and paint could be concealing a threaded or crimped cap encapsulating energetic materials within the shell."A radiographic inspection would also determine if there was an empty hollow cavity, one filled with a presumed explosive material, or if the shell was in fact a steel slug," said EOD Staff Sgt.Tyler Bickston.This physical and X-ray inspection validated the initial assessment that the shell was solid steel and that there was no explosive loaded into the shell. The item was a solid steel slug, and verified inert with no tracer installed as in the M79.ARDEC EOD brought the shell back to Picatinny Arsenal for further study since the museum did not want to keep the item."Layers of paint that had been applied over the years were stripped, followed by a search for any markings or lot numbers," Bickston said.A bump map image created by EOD from a photo of the rear of the shell showed what appeared to be a 3-inch marking and a remnant of a lot number, but it was too worn to reveal a clear identification.Bickston made an interesting discovery upon further examination. "The rotating band on this shell was made of copper, not brass, and was much thinner than the band on the M79," he noted. This discovery confirmed that this shell was indeed much older than originally thought.The rotating band design was similar to British and French bands from the late 1800s through World War I, so this was a good indicator of the item's age.Ranu found an ordnance handbook in the historian archive for a Model 1902 3-inch Field Gun, published in June 1917. The handbook lists a 3-inch Common Steel Shell that matched the physical size and external shape characteristics of the mystery item retrieved from the museum. The rotating band, double case crimp grooves, length, diameter, and weight of the 3-inch Common Steel shell all synced with the observed characteristics of the mystery item recorded by EOD.The discrepancy was that, similar to the World War II counterparts, the standard 3-inch shell depicted in the 1917 handbook is also loaded with an Explosive D bursting charge with a base detonating fuze installed.The manufacturing of the shell would have had the shell body with a hollowed out base before installing the rotating band, so it is very unlikely that this was an in-process manufacturing reject.Since all other characteristics match and the rotating band already installed, the conclusion was that the mystery item must have been either a training aid or a display model."The mystery item turned out to be benign, but that cannot be assumed with every historic ordnance item," Bickston said.Civilians who discover an ordnance item of unknown origin and condition are advised to treat it as if it were live.Call the experts. Do not handle it yourself. Only qualified EOD technicians with the proper training can determine the status of an item, and render an explosive-loaded item safe.Though it took much time, effort and persistence, the ordnance "History Detectives" at Picatinny Arsenal were able to close the book on "The Case of the Mysterious Doorstop."