MrMitus, I didn't see this mentioned before, but you might want to try some new brass. For a relatively small investment you can get some Winchester or Remington .223 brass. One of the things this will do is eliminate many of the issues you've been having with once (or more) fired brass. It will also give you a pretty decent reference point b/c the new brass will be within SAAMI specs.
There are different opinions about sizing new brass, some of those opinions vehemently stated. But, ceteris paribus, you are far safer loading new brass straight out of the bag than jamming up your AR or worse getting an over-pressure destructive disassembly. I've done it both ways and have never encountered a problem loading new brass without further prep.
"I'm your huckleberry."