Usually get consistent neck tension on any of the sizing dies, you're just changing how much tension by switching from a SAAMI spec to bushing die or by switching bushing sizes. The bushings come in various ID sizes (.001 increments that I've seen) and you select one that makes the case neck ID about .001-.002 smaller than the bullet OD. This means you need to account for the case thickness. Easiest way is probably to measure the OD of a loaded round with the bullet and case of your choice. You could also measure case thickness (multiply by two since it's a circle) and bullet OD and add all that up.How do the FL sizing dies still create a consistent neck tension for each round? Does the bushing dies just let you adjust the neck sizing to adjust the amount of neck tension? Am I understanding that correctly?