Bullet casters what does zinc contamination look like on a bullet ? I bought 2 separate batches of .577 minie balls the first batch shot well . The second batch when I opened looked different dark splotches all over the bullets . They shot horrible I grabbed the last box of the first batch and shot some as a control they shot fine both miked out same on my caliper . It was almost like the second batch was to hard to expand into the rifling . Now that hunting is down to its last month I’m gearing up for my civil war carbines so I’m trying to figure out which way to go thanks for any help .