Could be work hardened brass if the chamber is OK. After checking the chamber I would try annealing the cases to see if this helps. For a single shot not much neck tension is needed so you could back the dies out and size less possibly. If you have an over sized chamber and or under sized dies ether sending them back to the manufacturer or polishing them yourself could help.
I wouldn’t do that. WW296 just like AA9 it’s always been stated that a heavy roll crimp was needed for proper ignition in magnum loads.
