It's once fired Norma .338 win mag brass, and sized in a new Forster full length sizing die. Cases are lubed wit Imperial Sizing Wax.
The ring of brass ahead of the belt is actually fairly substantial, and looks like it could offset the headspacing, but I haven't noticed any different in chambering or accuracy.
What is causing it, and do I need to get rid of the excess brass?
Is there anything I can do to remedy it?
Could it be an oversized chamber? Undersize die? Oversize brass?