Sizes your case neck in the Wilson Neck Die or Wilson Bushing Type Full Length Sizing Die
To figure out what size you need see formula below
Made In the U.S.A.

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

To figure out what size to order... 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)