Weapon editing

[StuG]

i was just curious as to how one can edit the mag capacity of the mg34? ive changed attributes in set/stuff/mgun including "{filling "ammo mgun" 50}" but the mg34 remains at 100 rounds ingame, trying to get the real loadout of the drum at 50 rounds, the mg42 is ok for changing that way np, but y the mg34 isnt?