Tossing this out there before going to bed. Is it possible that this is happening because I haven't sorted brass by length or brand? I know I have some brass that's .742 long up to .748 and now I'm noticing that I have some that measure at .738. I'm thinking that may have messed with my crimp.
Those cases are within SAAMI specs for length: 0.744" to 0.754", so that should not be the problem, the case should accept them all with no length issues. No results with the black marker rubbing off any problem cartridges?
I'm going to suggest a silly thing: is your case gauge clean? If there was any dirt, excess lube or metal filings in it, it might affect the fit, no?
http://www.saami.org/PubResources/CC_Drawings/Pistol/9mm%20Luger%20-%209mm%20Luger%20+P.pdf


















































