Nosediving 9mm Handloads, Crimp Issue

[MaduroBU]

UPDATE: The issue was a poorly adjusted sizing die. Case mouths were 0.355" wide after sizing. Re-checked sizing die and sure enough it was 1/4" above the shell holder plate at top of stroke. Fixed that and now the necks are at 0.351" after sizing.

Lesson learned: Just because you assume that something was so basic that you could not have screwed it up doesn't mean that it isn't worth rechecking. The proverbial "Is it plugged in?"

A big thanks to all who helped me sort through my foolish error.