Start with 100 in each and then work your way up from there. Try to keep them all the same. One sneaky thing you can do is overload your outermost turrets or turrets most likely to get soaked first by attackers. If your outermost/first soaked turrets have 100 bullets, your enemies will have no fear to march on. If the first turrets they come across have 100's of bullets in them, it might make them think before continuing. The best is completely full turret, your best is your best...........do your best.