"The Hornady match Grade Dies feature interchangeable neck sizing bushings that are self centering. The bushings allow the user to size the case neck to the bullet tension you desire."

I plan to use this die to neck-size cases fire-formed in my .308 palma rifle chamber. How do I know what bullet tension is desired, and therefore what neck sizing bushing to use?

That is easy; use the bushing from which, ammunition made with it, shoots the best. That is why they give you a selection. No one can tell you which one, but your rifle can.

I've pondered the same question. (How much is correct, and how to measure.) I'm surprised RCBS, Redding or other manufacturer has not yet made a tool.

I thought about making one. In the meantime, maybe use an inertial bullet puller.

"xxxx xxxxxx took an axe,
Gave her father 40 whacks.
When she saw what she had done,
She gave her mother 41."

Just kidding. Too crude.

Measure a loaded rounds neck diameter. Buy a bushing .002" smaller as a start. If you only want to buy one bushing, go .003" smaller, and use the expander. You will end up buying about 3 bushings. Most will use .002" neck tension. Measure the neck before and after seating a bullet. On seating, the neck should expand .002"

quote:

Originally posted by 243winxb:
Measure a loaded rounds neck diameter.

Thanks. Good suggestion. That thought actually occurred to me after I posted the original question. The fire-formed cases I mentioned above are from commercial precision ammo (Lapua brass) that shoots very well in this rifle, so that source will be my loaded-round measured-reference example diameter.

I've had my best success with .002 and .003 under bushings. .001 typically leaves the bullet too loose. Necks wear a bit with use, and the line between "barely enough" and "almost enough" is very thin.

There is a bit of spring-back on a sized case, (or fired case for that matter)and using a .003 bushing might get you closer to .002 tension than .003.