I haven't read every post in detail, so I apologize if this is off base.
You're problem with loaded rounds not chambering actually sounds like a buller seater die mis adjustment to me. I've done this and found out the hard way.
If you don't unscrew the die one turn after setting it to kiss the shell holder, you are likely to crush the neck down a bit when you seat a bullet. When you push the neck down, it bulges the shoulders out slightly to where they won't chamber. It can be easy to miss, measure it with your calipers and you'll see it.
You can usually take the decapping pin and screw out of the sizing die and run them slowly back into the die to get the shoulder pressed back in, that should get them to chamber.
The other possibility is that you didn't lube the case neck and when you pull the expander button back thru the neck it pulled the shoulder back up.
Sorry for rambling, hope you get it figured out...
Last edited by Pittu; 03/22/14.
