Would an AI chamber fix my problem

[degreen]

I just checked some neck diameters on some fired cases and some loaded rounds. The loaded rounds measured .367, and the fired rounds measured .372.

 

[Rflshootr]

Then it's not a neck issue. .005-.006 is plenty of neck clearance. Does the brass have a polished ring right above the extractor groove where the beginning of the chamber is after firing?