It takes at least two one-shot kills with a sniper rifle with the ability that returns ammo to the reserve to net you one round in the reserve. They're not lying, but come on, infinite ammo? Ice breaker and invective already provide a minor exploit (if it can even be called that) to provide you with unlimited special ammo (in PvE) and with the rate at which primary ammo drops, it shouldn't be a huge problem.