If you know your rifle, and can hit a 3" target every time, you should not have any problem with 100% detonation when shooting Tannerite® brand targets. If you are shooting long range and there is a chance of a miss, graze, glancing hit, or skip-fire (round skipping into the target due to a slightly low hit) you should wrap the target in red duck-tape. This prevents leakage or spills due to a bad hit and you may continue shooting the target until you make a solid hit. This is what we do when shooting 4-6 hundred meters and it prevents lids being blown off or other similar scenarios.
For safety reasons and to prevent skip-fires, you should always suspend the rifle target off the ground. Many customers tape it to a wooden rod about 2 feet off the ground, while others suspend it with a rope or string from a tree branch. Always know your back-stop when doing this, so that there is no chance of a stray round.