With bushing dies there is no need to lube the inside of the neck unless you are running both the bushing and the expander ball. If that is done you are defeating the reason for the bushing. If you are running a standard die that uses the expander ball then Yes the inside of the neck needs to be lubed. (I use a bore swab to lightly lube the inside of the neck) Be sure and solvent clean the cases
if inside lube is used in the necks.
I have not had any problems with Donuts forming inside of the necks after fire forming. Sometimes bumping the shoulder can sometimes cause this if over done. Normally with minimal sizing, cases only grow in length and need an occasional trimming.
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