You should be VERY careful with that 2CM FLAK round. Even though I believe that those fuzes have inertial safeties that need to be spun up to arm, the fuze's gaine which sits down into the TNT filler gets more and more unstable with age as does the TNT that surrounds it.
under NO circumstances attempt to unscrew the fuze from the body of the projectile. The TNT was poured with paraffin which over the years out-gasses carrying raw nitroglycerine into the threads of the screw. You try to unscrew it and BINGO. You are strawberry jam.