Re: Type S Bushing Dies
For me, the first consideration is the neck thickness of the brass or what thickness you are going to turn the necks to. The bushing dies size the outside of the neck to a certain dimension. In doing so, they will push all the variations in neck thickness to the inside of the neck. So that is why I only use the bushing dies on necks that I have turned to a consistant thickness.
It will also depend on whether you have a tight necked chamber. For instance on a 338 RUM I have a fired case OD neck measurement of .366". Since I want .003" clearance that would mean I want a loaded OD neck measurement of .363". The bushing size will then depend upon how much bullet grip I want, say .002", then the bushing size will be .361".
Then I calculate what thickness to turn to by subtracting the caliber from the desired loaded OD neck and dividing by 2
and turn the necks to that .0125".
On a factory chamber where there is a lot of neck clearance then I will measure all the brass neck variance and turn to the lowest common measurement. If the brass varied from .013" to .015" then I would turn to .013". So then the bushing would be chosen by adding the caliber and 2 times the neck thickness and subtracting the bullet grip
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