Read this, it might help.
It is possible that your dwell time is short, if it is the extraction happens while the case pressure is high.
This link explains it.
http://m14forum.com/m14/103625-dwell-time-pertains-m14-how-adjust.html
Another possible solution/problem, is your chamber clean and smooth, brass can stick in the chamber, if it does it takes more force to extract.
Jim
It is possible that your dwell time is short, if it is the extraction happens while the case pressure is high.
This link explains it.
http://m14forum.com/m14/103625-dwell-time-pertains-m14-how-adjust.html
Another possible solution/problem, is your chamber clean and smooth, brass can stick in the chamber, if it does it takes more force to extract.
Jim