By: Boyd Allen

Boyd Allen — Wed, 29 Apr 2026 16:46:26 +0000

There is a lot more to this than OD to ID runout. I have a carbide bushing that measures perfect in that respect. They are precision ground, rather than turned and polished. One of the major issues is the amount that the OD of a fired neck is larger than the sizing diameter of a bushing and the configuration of the lead in chamfer or radius. Several of us have tried the SAC Wilson style bushings and can confidently report that they produce less runout. This is because of a unique configuration in the portion that captures the end of the fired neck. Recently I did an experiment that further reinforces this angle by sizing necks with a collet die before further reducing them with a conventional bushing. They were much straighter than the same cases sized with the bushing alone.

Comments on: Neck Bushing Uniformity Tested — Results Are Surprising

By: Boyd Allen