CHICAGO -- When the Field Museum decided to clean its arsenal of 300 to 400 handguns and hand-held cannons, it found some were loaded and ready to shoot.

Black powder, with the power of six sticks of dynamite and very unstable, was found in powder horns, a rifle, a pistol and two cannons.

"They were all muzzleloading black powder weapons," said William Pestle, collections manager in the museum's department of anthropology.

Because the volatility of black powder increases over time, a bump could have set the weapons off, said Pestle, who launched the weapons cleanup last year.

"They could have done a fair amount of damage had something horrible happened," he said, adding that none of the loaded weapons was on display.

The museum is building a collection of guns and other weapons, including whaling spears, to explore colonialism and mistreatment of the environment. It hired Al Potyen, a gun expert at Wheaton's Cantigny Museum, to examine the weapons.

"I was surprised at how few of them were loaded," Potyen said, noting that before they were antiques, the weapons had to be kept ready to shoot. If a family gun was handed on to a relative, whoever inherited it often did not know it was loaded.

Potyen checked the guns by gingerly running a wooden dowel down the barrels. Obstruction within the last six inches indicated a charge, he said. The powder found was destroyed by breaking it down in warm, soapy water.

Field anthropologists use the weapons to document how people hunted, defended themselves, or waged war. The collection has guns from as early as the 16th century, including a small, four-barrel flintlock pistol that could shoot all barrels at once, or one at a time, and a "punt gun," a 9-foot-long, 75-pound, iron-barreled weapon used to hunt birds.

Pestle says his wish list includes a Sharp's buffalo rifle, used to wipe out the buffalo in the United States -- "an important event in human interaction with nature."