The cutter pilot has an initial diameter of 6.12 mm then grows on a taper of 0.5 ° up to a diameter of 6.14 mm. This creates a close fit of the neck to the pilot. The pilot being carbide can be cleaned frequently with 1000 grit sandpaper to remove any traces of metal (brass) deposited on it during the turning operations without altering its diameter. This phenomenon, known as galling, occurs when turning at too high a speed, or with inadequate lubrication. The recommended speed for turning is roughly 60 RPM.
1. Lubricate the case prior to inserting into the expander/sizer die.
2. Lubricate the inside of the neck with a nylon brush and moly grease.
4. Let the cases stand for at least 24 hours.
5. Turn the necks down, removing 80% of the desired total amount to be removed.
6. Let the cases stand for at least 24 hours.
7. Size the necks down with a full length die using the appropriate bushing.
8. Run the case through expander die as in step 3 to bring the neck ID back to 6.14 mm, thus re-creating the proper tension on the neck of the neck turner pilot.
9. Let the cases stand for at least 24 hours.
10. Turn the necks again to the final thickness.
You should also lubricate the blade while cutting the neck, thus avoiding problems of galling on the blade and increasing the smoothness of cut.
I am sure many of you will wonder if all this effort is worthwhile, but I must say that the search for an ever increasing level of precision carries with it a duty to experiment, to seek new solutions. Although the results themselves are comforting, the satisfaction of having contributed to the sport amply rewards the effort and expense involved.