Bulge around the botttom

[Roadkill]

Settle down Ed, I'm referring to ammo. Been categorizing my 9mm cases into long -.745+", just right- .739-741", and short - .735-738". As I'd get a long or short one I'd toss it in a marked coffe can. Finally got up enough and loaded the long ones first, kept oal right, used 5.6g of unique with a 225g cast bullet. No problems at all. Then used the short ones. Same everything. Big problems. Failure to feed repeatedly. Slide would not close on my P-1 or the HPC. Finally gave up, brought them back, problem was the short ones were bulging at the bottom where they would not fit in the sizer die.
Measured them, allowed was .394", all were above 390", the just right and long ones were all about .384-388". Mixed brass, all used several times but the short ones. Am I doing something wrong again? And what is the recommended load for 255g lrn .45 in Unique? My books only go up to 230g but if patterns hold it should be about 6.5g. Last question. My 1911A1 firing pin retaining plate keeps on dropping down and locking up the slide. Would a new spring keep that from happening or do I need a new plate?

Thanks

rk