They even so do have non-uniform lengths. If you do not trust me, take a batch of brass with the exact same headstamp and measure their lengths - I've measured hundreds, they do as a point differ in duration. Together with the FC brass I calculated, Severe unfold was around https://9mm-bullet-reloading18417.full-design.com/getting-my-9mm-reloading-brass-to-work-79150051