Just having the weapon in the backpack is way too boring and restrictive :
If this guy will be stuck to use a single weapon at time he would have had been killed with all his team, of course we don't talk about using 2 weapon at time in 2 different direction, just have 2 on us, exactly like real life military do. It this image they are soldier in REAL LIFE operation, not in training, no airsoft. Some example here of soldier who have several primary weapon :
