One of the wonders to people who saw the damage it caused was the lack of it. There are bullet holes but the glass didn't shatter. Rather, it broke into a frosted web but stayed in place. The airport was going to cover the surface with a film and then replace it.

This is because the gun is basically 19^th century technology - this type of revolver is sometimes called the "gun that won the West" - while the glass used in airports is up-to-the-minute technology developed in the age of the terrorist.

The type of revolver is still produced but hasn't been used by the military or the police for 60 years. The original version was designed by the American firm, Smith & Wesson in 1877 and produced from then until the present day, though only in very small batches.

A version of the revolver was used by the British military from 1922 to 1963, a period including the Second World War and Korea. It was also used by Australian soldiers. The latest version is still available on Australian websites for $1570.

But - and there's a big but - legal ownership demands very rigorous background checks. Anybody with a criminal record would be barred from purchase.

Experts in firearms told The Canberra Times that the weapon was basically old technology. It was "outdated", according to Thomas Darby of the Shooters Warehouse in Canberra.

"To get a Smith & Wesson legally, you would have to pass a criminal background check. To get one illegally would be very, very difficult," he said.

It is still used legally by enthusiasts of "cowboy-style shooting" but in very controlled circumstances.

But tests done to FBI standards with different brands of ammunition indicate that the bullet doesn't travel fast compared to those from other more modern hand guns. It would not be a chosen weapon in Texas, for example, by people seeking to defend themselves.

Its ability to shatter tough objects is limited - and airport glass is now very tough because of lessons learnt in the Oklahoma City bombing in 1975 when a right-wing extremist blew up the Alfred P Murrah Federal Building, killing 167 people.

Many of the dead were killed by shards of glass.

"When a terrorist bomb explodes in an urban area, it produces devastating effects, including structural and non-structural damage to buildings, injuries, and deaths. Numerous injuries in explosions result directly and indirectly from window glass failure," according to The Journal of Performance of Constructed Facilities.

The results prompted governments, scientists and companies to investigate how to make glass bomb proof.

Laminated glass is glass with ultra-thin layers of polymers embedded in it - rubber or plastic are types of polymer. This means that when the glass shatters these very thin membranes of non-glass hold it together so it shatters within itself in a kind of spider web effect. There are no shards shooting out.

Canberra Airport is not discussing the types of materials it uses. But there are industry standards, not just for airports but for sensitive buildings (it would be a surprise if government buildings including ASIO didn't have anti-terrorism glass).

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