K+M Expand Mandrel for Expand Iron Assembly, 25 Calibre

Virgin/competition brass isn't quite ready to neck turn when you buy it. And the commercial die manufacturers have no set standards for the expander button in their dies. Large variations from manufacturer to manufacturer make it necessary to properly size the inside diameter before turning. Don't be fooled by slick talk. The turning pilot cannot be used to correctly expand the case neck because of the elasticity of the brass; it will spring back and be too tight for proper neck turning. The expand mandrels will iron out (smooth) and slightly expand the case neck so the brass will spring back to the correct size needed to neck turn your pet brass.