They nonetheless do have non-uniform lengths. If you don't trust me, take a batch of brass with exactly the same headstamp and evaluate their lengths - I've measured hundreds, they do being a fact differ in length. Along with the FC brass I measured, extreme spread was about 10 hundreds. https://knoxnizri.dreamyblogs.com/37252388/the-smart-trick-of-reloading-9mm-ammo-that-nobody-is-discussing