When the Senate debated legislation last December to ban "non-detectable" plastic guns, Sen. James McClure, R-Idaho, said the idea made about as much sense as barring Buck Rogers from strapping on an invisible six-shooter.

McClure, a key National Rifle Association supporter, acknowledged plastic or ceramic guns could pose security risks at airports, courthouses and other sensitive facilities protected by metal detectors that is, if such guns actually existed."There is presently no such thing as an all-plastic gun," the Idaho Republican insisted. "I have found no reason to believe that such firearms could be developed for sale in the near future.

"For all the good this bill will do, we might as well be outlawing invisible guns," he gibed, adding that Congress ought to be worried about real threats such as plastic explosives, "not some imaginary Buck Rogers item."

The Senate voted 47-42 against the legislation in what appeared to be another albeit narrow victory for the NRA.

But only two months later, the "imaginary" guns apparently had taken on enough substance to persuade McClure to introduce his own legislation to outlaw them.

Even more stunningly, the NRA openly endorsed McClure's measure, the first time in recent memory the group has publicly blessed legislation to restrict gun rights before congressional approval was all but sealed.

McClure explained that he now recognized there is "understandable concern" that plastic guns could become available before effective detection equipment is developed.

And David Conover, an NRA lobbyist, said the slim margin of the Senate vote had caused "an evolution of thought" on the plastic gun issue within his organization.

"Nobody wants to go around arguing there should be undetectable guns," he said. "That is just not going to fly in the media and public perception.

"Hardline opposition is not going to carry the day on some issues and this is one of them. We expect this to become law before the end of the year."