L.E. Wilson Neck Sizing Die Bushing 337

The Neck Die Bushing fits in the Neck Die and sizes the case neck to grip the bullet.

To calculate bushing size... Measure the diameter of a loaded round where the bullet sits in the neck (Ex. .268).  Now subtract .002 to .003 from that number.  

.268 -.002 = .266 Bushing

Another way is to measure your wall thickness and multiply by 2 and add bullet diameter.  Then subtract .002 to .003 from that number.

.012 Wall Thickness x 2 = .024

.243 Bullet Diameter

Example:  .243 + .024 = .267   Now subtract .003 (.267 - .003 = .264 Bushing)