Career total of 50 shots on explosivesThis is a cumulative achievement that should unlock naturally over the course of all game modes. Explosives that count are grenades on an enemy's belt, mines, cannon shells, barrels, fuel tanks; anything that explodes. All you need to do is shoot a total of 50 explosives.
This should naturally unlock during your campaign playthroughs but if it doesn't, there are many ways to farm this. One is to keep reloading checkpoints where there is an explosive nearby. Another is to set all of your mines and dynamite out on the ground and shoot each one individually (making sure that they’re not close enough where they will set off a chain reaction) then reload the checkpoint and repeat. Finally, there is a checkpoint as the tank appears in Mission 1, 'Schoneberg Convoy'. If you are in an elevated position, you can shoot the fuel cap to destroy the tank then keep reloading the checkpoint.
This cumulative stat is not tracked in Career Stats.