Originally Posted By: VarminterrorSure sounds great to say the neck tension is the same, but it is absolutely not true.
A 13thou neck batch of Hornady on my bench ran through a .269” bushing would yield a slip fit of 0.243” on a 6mm bullet. The 14.5 thou lot of Lapua beside it yields 3 thou neck tension.
It’s really that simple. Dies push on the outside, if they yield the same OD on the necks, the ID’s will not be the same for different neck thicknesses.
And that is the exact downfall of bushings! When your running bushing dies *without and expander button* you have to account for neck wall thickness. Brand A brass vs brand B brass will often require the use of a different bushing to get the same neck tension.
In a standard FL die, and even in a bushing die *when using an expander button* your neck tension is set by the diameter of the expander. I don't care if the die or bushing sizes the neck down 10 thou, if your expander is .240 diameter... Guess what... Your inside neck diameter will be. 240 or very close to it depending on brass hardness.
So to my point, with a full length standard die set virtually all brands of brass will mic the same inside diameter +/- a small amount. Now if you turned necks down for 13 thou thick to say 8 thou thick, you will probably have trouble getting any neck tension because the brass wall thickness is so much thinner than what it was intended to be resulting in the neck portion of the die being too big to properly size down the neck which will make it so the expander ball cannot do its job and open the necks back up to the right diameter.
Typical off the shelf dies for something like a 223 are often times hard on the brass because they size the necks down alot and then bring them back up to size with the button. What yiu have to remember with these custom made dies is the reamers wer cut to spec based on the chamber print used to cut the barrels and on actual fired casings from such barrels. These dies, Hornady in particular, don't over work the brass nearly as much as a standard Sammi off the shelf die might