They on the other hand do have non-uniform lengths. If you don't trust me, have a batch of brass with exactly the same headstamp and evaluate their lengths - I have measured hundreds, they do as being a simple fact change in length. Along with the FC brass I calculated, https://9mmdirtyoncefiredbrass69819.ampblogs.com/the-2-minute-rule-for-reloading-9mm-ammo-73021652