When the SS firing squads are executing the men, there is a very brief close up of a German soldier with his rifle raised and his finger on the trigger. However, the bolt of the rifle is completely open and a cartridge can be seen in the breech not completely seated in the chamber. A bolt action rifle will not fire in such a condition.
When the soldier from the gas truck shoots himself in the head with a Luger, the pistol's action does not cycle, and no spent cartridge is ejected.