Just got me a new Proof SS barrel in 6 Dasher all mounted up this past week. The brass i have for it is used and has actually been used in 2 other barrels. In preparation for the new barrel I bought a ring sizer die to whip the head/web area into shape. The rounds chamber fine, no resistance to speak of. I can load and eject the rounds just fine. When they are fired they will absolutely not come out of the chamber. I fired 15 shots and had to use a cleaning rod to gently tap each one out. Stuck enough that it was taking shavings off the rim if I pulled the bolt enough. Brass doesn't have any obvious markings on it. Not sure where to go next.