Gun ban would protect more than 2,200 firearms

"It's irrelevant," Edmund Mireles, an FBI agent who survived the Miami shootout, said of the differences in features. "They're equally dangerous."

Mark D. Jones, a senior law enforcement adviser for the University of Chicago Crime Lab, said the folding stock does not affect the firearm's lethal potential.

"Given that both firearms will accept a 30 round or larger magazine, it renders the differences between them entirely cosmetic," Jones said.

Kristen Rand, the legislative director at the Washington-based Violence Policy Center, said the Ruger Mini-14 model that would be banned under Feinstein's legislation is easier to hold while firing because it has a pistol grip, and it's easier to hide because it has a collapsible stock. That's what makes it more dangerous that the Ruger Mini-14 with the fixed stock which would be exempted under the Feinstein bill, she said.

"And that's supposed to save somebody's life?" asked Hanlon, the FBI agent shot alongside Mireles.

Hanlon considered the differences between the two models and whether the events of April 11, 1986, would have been different if the shooter used a Ruger Mini-14 with a fixed stock. "I don't think it would have changed a damn thing," he said. "I don't see what makes that gun less dangerous."

Follow Eileen Sullivan on Twitter: http://twitter.com/esullivanap