A 9mm cartridge should headspace on the case mouth. If there is enough taper crimp for a round to push through the chamber ridge that stops the cartridge and establishes headspace, the cartridge is defective.
A secondary cause might relate to the length of the entire toggle train and any play caused by wear at any of the axle pins, and where the breech face has been positioned relative to the head of the cartridge. You might also look at the fitting and condition of the extractor.
__________________
 Igitur si vis pacem, para bellum -
- Therefore if you want peace, prepare for war.
|