I’ve never seen the stuff in real life, but if I recall correctly, Tannerite isn’t just a shock-sensitive explosive. It’s a binary explosive; you have to mix two components before it becomes a shock-sensitive explosive, which lets you store the stuff safely.
That looks like a sealed, commercially-made jar of the stuff, so I assume that whatever is in that jar probably is only one binary component of the shock-sensitive explosive, and that shooting it isn’t going to do a lot other than making a big mess.
Tannerite is a brand of binary explosive targets used for firearms practice and sold in kit form.[1][2] The targets comprise a combination of oxidizers and a fuel, primarily aluminium powder, that is supplied as two separate components that are mixed by the user. The combination is relatively stable when subjected to forces less severe than a high-velocity bullet impact. A hammer blow, the product being dropped, or impact from a low-velocity bullet or shotgun blast will not initiate a reaction. It is also designed to be non-flammable[3] (the reaction cannot be triggered by a burning fuse or electricity), although its explosion can ignite flammable material.
Assuming that they’re using correct proportions, the mixed stuff is apparently gray pellets (white pellets plus gray powder). The stuff in the image is white, unmixed.