RCBS Tungsten Coated Neck Sizing Bushings are designed for use with RCBS Gold Medal Match neck sizing dies and help achieve the right tension on the bullet without traditional case lube.
The bushings are coated with Tungsten Disulfide (WS2) for anti-friction properties and should be self-centering to ensure proper alignment with the case neck.
To select the correct bushing size, measure the loaded cartridge's outside neck diameter and subtract .002"-.003", or calculate based on neck wall thickness and bullet diameter, then subtract the same.