A GUY WALKED into Frank Sciarra's Montgomeryville gun shop a few years ago, looking to unload 20 guns.

For a cool $20,000, Sciarra purchased the weapons - mostly rifles - and sold many of them to customers who frequented his store, Archery and Gun Outfitters, on Route 309.

"Everything was fine until about a month later, when the ATF [Bureau of Alcohol, Tobacco, Firearms and Explosives] and Montgomeryville police showed up," Sciarra said.

"Turns out they had arrested the guy who sold me the weapons. They said he had stolen 60 guns from a storage facility, and they wanted 'em back."

Sciarra, 60, was in a pickle, the kind every gun- shop owner dreads.

He had to track down the new owners and persuade them to surrender the firearms they had purchased legitimately.

He lost whatever money he made off the sales and had the added misery of knowing that he had sold stolen weapons.

Disgusted by the experience, Sciarra sold his shop in 2007.

About a year later, he and his business partner, longtime Philadelphia radio personality Don Cannon, launched www.firearmsfax.com, a Web site they hope will prevent other gun-shop owners from having the same experience.

The Web site lists serial numbers of lost or stolen firearms that people can access for $19.95 a month, Sciarra said. Police can access the database for free.

The database has collected "several hundred thousand" serial numbers that have been supplied by insurance companies, gun owners and law-enforcement agencies across the country, he said.

"There are about a half-million guns stolen on average every year," Sciarra said.

"This site can offer you peace of mind if someone walks into your shop and tries to sell you a bunch of weapons. You can find out if the gun's hot, call the police, and we'll get a criminal off the street."