Plutonium

I don't know this is a bug or what, but in buried, when i use the mystery box i only get the same guns (HAMR, M1216, Galil, DSR50, SMR and War Machine) the monkey bombs and the time bomb. I don't know if this is because of the mod or I'm just unlucky (this happened in the 4 games I played in the last 2 days).