For ATF bomb experts, it's what's leftover from a blast that counts

Inside look at ATF's bomb testing range

Federal investigators are still examining the explosives recovered after last month's bombing spree in Austin, Texas. CBS News' Jeff Pegues got a look inside the secure site in Huntsville, Alabama, where the bureau of Alcohol, Tobacco, Firearms and Explosives works to prevent future attacks.  

At the ATF's explosive testing range you can feel the power of the blasts – even from 200 hundred yards away. There, ATF agents have been studying homemade explosions similar to the spate of bombs that left Austin on edge last month.

The ATF sent hundreds of agents to Austin and followed thousands of leads. Some of the most important pieces of evidence from the Austin attacks are the bomb fragments themselves, many of which are being held in a secure lab outside Washington, D.C. The ATF's J.D. Underwood said what is left of an explosive device is preserved for a reason.

"We're going to try to recreate. We're going to collect as much of the evidence left over from the bomb. It doesn't all go away," Underwood said.

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Crater left behind by a detonated bomb at the ATF's explosive testing range.  CBS News

The devastation left behind by the explosions is stunning. Craters from the blast leave an area looking like the surface of the moon.
 
At the ATF's National Center for Explosives Training and Research in Huntsville, agents stockpile pieces used to make homemade bombs. There are batteries, timers, switches and different types of liquids and powders for explosives.
 
Tom Chittum, the special agent in charge of the Washington field division, says the ease of making bombs has increased their frequency.

"The numbers are high. I think the average person would be surprised to know that ATF investigates hundreds of bombings a year," Chittum said.

In 2017, ATF labs helped close about 314 explosives cases. The Austin bombing investigation is still an open case.