How do you tell if a powder is bad just opened a new can of h 4198 and there is no smell but most of the grains look as if greenish as if brass had tarnished . opened another can and the same thing checked and they have the same lot number .both were sealed it has not been very long since I bought them ( in last 2 years). But I bought them from a small gun store so not sure how long they had it. Just wondering if it is safe to load with? Any opinions. Thanks