Polish the neck of the die, it appears some cutting compound was left in the shoulder area that made it's way up into the neck with the passage of your cases.
If you don't remove the compound and polish the neck, the scratches will stay.
Have had similar problems with all dies, the factory doesn't always remove all the compound, worst I've seen was my RCBS 264WM die, the compound was thick in there.
Cheers.
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