Tannerite is not quite classified as an explosive by the ATF (it's under binary explosive, as they separate it down to), they classify it the same as black powder once the two components are mixed up to create tannerite.
There is an exception for tannerite, just the same as black powder. You can store, mix, and detonate for personal recreational use. But it is limited to 20 pounds. Nebraska follows the suit with this. Other wise, black powder would not be allowed and the rifles would be useless (FYI: there is no permit of any kind, no background check, etc. for a black powder pistol/rifle...it's a pick up and purchase, no paperwork of any kind...same for all the components like black powder, primers, black powder balls, etc.).
"Storage regulations do not apply to binary explosives until they are mixed."
"Persons manufacturing explosives for their own personal, non-business use only (e.g., personal target practice) are not required to have a Federal explosives license or permit."
https://www.atf.gov/explosives/how-to/binary-explosives.html"...will not apply to..."
"The storage or possession of or dealing in black powder used for recreation purposes by a sportsperson"
http://www.nebraskalegislature.gov/laws/statutes.php?statute=28-1239This is the series of laws applicable here. It is large and can be confusing. Their are many repeals in there as well.
http://www.nebraskalegislature.gov/laws/browse-chapters.php?chapter=28Now don't get confused with the news, as we all know they only tell as much to push their agenda and then twist the rest. There was a couple of guys that got cited/arrested for exploding 50 pounds without a permit (that incident out in kearney), obviously well over the amount the exception allows.
Also, if tannerite was classified as an explosive, places like Cabelas would not be able to sell it. Only a few of the Cabelas have the FEL (same as FFL, only for explosives though) and the LaVista store is not one of them, but they have tannerite and black powder.