Hardened stainless steel neck bushing from L.E. Wilson is marked with a size indicating the middle diameter and has a .003” taper for precise sizing adjustments.
For emergency use or fine-tuning, the bushing can be flipped to achieve a tighter sizing if brass has hardened or to provide less “squeeze” than the next smaller standard bushing.
To select the correct bushing size, subtract .002"-.003" from the loaded cartridge's outside neck diameter or calculate based on neck wall thickness, bullet diameter, and desired spring back.