Conventional neck size dies do not support the body and can induce runout. I had a 308 neck die that put .006-.007 runout on straight cases. Now I use only Lee Collet neck sizers. Also partial full length sizing accomplishes minimal case working and you can always FL size when needed.
I agree. My runout numbers went down rather drastically after using Lee Collet neck sizing dies. I'm a big believer in them. As you say, when the need arises, now I just use a body die to bump shoulders a touch. My brass most definitely lasts longer than FL sizing every time.
