HUNTSVILLE, AL -- When 81-year-old Carl Craig walked into Madison Guns & Ammo Tuesday, he didn't know the gun he was carrying was an illegal weapon.

Craig had a .410 gauge pistol, made sometime in the late 1920s or early 1930s.

"The reason it is illegal is that it's a handgun that fires a shotgun shell," said David Hyche, Bureau of Alcohol, Tobacco and Firearms resident agent in Huntsville and Birmingham.

The gun was handed down to Craig by his father about 60 years ago, but it's been kept in a box for most of that time. Earlier last week, Craig decided to have it appraised.

"It's a pretty unusual weapon," he said. "It's a shotgun, but it's a pistol."

After putting the gun's information into the computer system at Madison Guns, the store was notified the weapon was illegal, requiring the store to hold it until local ATF officers could inspect the gun.

While Craig didn't understand how the store could legally keep his personal property, he left without his gun. The next morning, he met with local ATF officers at the store to find out what the law said about his gun.

Tim Knox, owner of Madison Guns, said he had no choice but to confiscate the gun and contact the ATF once the computer said it was an illegal weapon.

"I could lose my federal firearms license, be fined up to $125,000 and go to prison for five years," Knox said. "My salesman could've been arrested, and Mr. Craig could've been arrested."

ATF's Hyche said Knox was correct in holding the gun, and ATF agents in Huntsville worked with Craig to make sure he could keep the gun.

To make this particular gun legal requires one of two things, Hyche said. Craig could have the gun rifled - have grooves cut into the barrel - or he could have the gun disassembled.

Before Craig left Madison Guns Wednesday, the gun was disassembled, and he was able to take the heirloom back home.

In 1934, the National Firearms Act outlawed short-barreled shotguns. Technically, Craig's antique gun is illegal under the law, but Hyche said the ATF's concern was figuring out a way to let Craig keep it.

"This happens all the time," he said. "We don't want (the gun) destroyed or take it away from the family."

He said it's common that people are left guns like this when family members die, and the best thing to do is contact the ATF.

"We don't want to charge any of those people," Hyche said. "We almost always find a way to accommodate the person."