In continuing with my series of asinine newbie questions, I have another three I couldn't find the answers to on my own. 1.) What causes 9mm case length to shorten? I guess it's just rifle/shouldered cases that lengthen when shot? I am assuming getting slammed by the breech face into the ridge to headspace at the mouth is the culprit? Is is usually more noticeable after, say, 5+ reloads of the same case? 2.) How short is "too short"? I've been studying my SAAMi specs and assuming the .754 is the max length, more or less, but what is the minimum? I have a few that seem much shorter than others and assuming no one trims 9mm brass nowadays, so wanted to ask. 3.) If a shorty slipped by me, what's impacted? During one of my overthinking sessions, I thought 1.) the bell will be jacked up if set for 'regular' sized brass...not as deep...or does the resizing die ever-so-slightly stretch it (thought it just re-forms the case shape, but I don't know) and 2.) the crimp (removing the bell) would be impacted, too...and thought 3.) the bullet won't be seated as far, being shorted by how much shorter the suspect case is relative the case I used when setting the OAL. I had (have) zero plans running plain brass through case gauge, but was checking a few cases and some factory rounds to get a feel for it and I assumed none would pass (thought looser glock chambers would expand them very slightly, but enough to fail the case gauge toward the head...some did fail like that...but some didn't. Some of the cases were short in the cause gauge, which raised the flag. The smallest case was .735 and just looked small enough that I checked the headstamp thinking .380. Some felt really light, too, and were also short...but all was 9mm. Not knowing better, I would probably have shot most of the short ones, as they were just recessed a little but not as much as the .735-.740s...would have tossed those. HOWEVER, without case gauging the brass before loading, I am not sure I would have caught them. I also thought though the case is shorter, it isn't necessarily a pressure concern, right? I am assuming to maintain the same OAL as the rounds with the full-size case, the bullet would be seated less deep and offsets the shorter case? (though not a linear relationship I am learning).