/> These self-centering, interchangeable neck bushings allow reloaders to precisely control bullet tension when using RCBS Gold Medal Match Series dies. This reduces work-hardening of the case-neck brass, extending case life and improving accuracy. To realize these benefits, high-quality brass with uniform neck thickness is recommended.
Neck-bushing size can be determined in two ways. One method is to measure the outside neck diameter of a loaded cartridge and subtract .002 to .003 inch, providing roughly .001 inch of brass spring-back for proper tension. The other method is to measure the case’s neck-wall thickness, multiply by two, add the bullet diameter, and subtract .001 inch. RCBS also recommends keeping bushings one to two sizes above and below the desired diameter.
SPECIFICATIONS
- Size: 0.309
