[SteveH]

https://en.wikipedia.org/wiki/Tannerite

two chemicals shipped together, when mixed, form an explosive that can only be set off by a high velocity (ie rifle) bullet.

i imagine it could be used as a detonator for larger explosions but someone more familiar with explosives could probably elaborate. for detonators, one has to be concerned about geometry, hydrodynamic forces, etc.

[ButThreeLeftsDo]

Tannerite makes targets that can be touched off with .22 rimfire.

[Newbomb Turk]

Ammonium nitrate by itself is not explosive. It requires some kind of hydrocarbon such as fuel oil, diesel or gasoline mixed with it to be an explosive. Tannerite could be the spark that sets that explosive off though because it comes in two parts and when mixed, Tannerite explodes when shot with a bullet.

So ammonium nitrate mixed with diesel fuel and put in a car with Tannerite could in theory be set off from a distance with a shot from a high powered rifle.

[Myrddin]

Most of the local gun shops sell Tannerite. My outdoor range prohibits using it. Have to take it off to some open BLM land. I have yet to see anyone buy or detonate any. Seeing it on YouTube is sufficient amusement.