I had some 30-06 military cases that had been reformed to 8 X 57 mm.
That brass had a lot of cases with thick necks ( up to and including .017 " )
I " outside " neck turn my brass.
I ordered a Hornady , 8 mm mandrel for my Hornady Neck Turning Tool.
Today , I turned my military necks to .012 " which is similar or identical to my R-P, 8 X 57 mm , commercial brass neck thicknesses.
They chamber smoothly now . ( With .017" thick necks, they chambered hard ).
As we all know the bullet in any cartridge has to have " release " . With the thick necks on my military brass , I didn't have that, so I would not fire them in that condition until the necks had been thinned to offer me the needed " release " that is necessary for safety.
My load to test these will be :
8 X 57 mm brass from reformed military 30-06 brass.
250 gr. NOE plain base 327331 RN cast bullets
Cast bullets sized to .325 "
Powder charge will be 8.5 grs. of International.
Pretty easy to see the necks where they have been turned.
They are uniform now.